"Fix" useless MinGW warnings.

Do I have to repeat it? Oh and also it produces warnings ONLY if given
function is used, so I guess the user code has *a lot* more warnings of
this kind.

src/Magnum/Buffer.h

@@ -879,7 +879,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
         Buffer(const Buffer&) = delete;
 
         /** @brief Move constructor */
-        Buffer(Buffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Buffer(Buffer&& other) noexcept;
 
         /**
          * @brief Destructor
@@ -893,7 +894,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
         Buffer& operator=(const Buffer&) = delete;
 
         /** @brief Move assignment */
-        Buffer& operator=(Buffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Buffer& operator=(Buffer&& other) noexcept;
 
         /** @brief OpenGL buffer ID */
         GLuint id() const { return _id; }
@@ -906,7 +908,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
          * to moved-from state.
          * @see @ref wrap()
          */
-        GLuint release();
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline GLuint release();
 
         #ifndef MAGNUM_TARGET_WEBGL
         /**
@@ -1065,7 +1068,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
          * @requires_gl Buffer data queries are not available in OpenGL ES and
          *      WebGL. Use @ref map() in OpenGL ES instead.
          */
-        template<class T = char> Containers::Array<T> data();
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        template<class T = char> inline Containers::Array<T> data();
 
         /**
          * @brief Buffer subdata
@@ -1083,7 +1087,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
          * @requires_gl Buffer data queries are not available in OpenGL ES and
          *      WebGL. Use @ref map() in OpenGL ES instead.
          */
-        template<class T = char> Containers::Array<T> subData(GLintptr offset, GLsizeiptr size);
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        template<class T = char> inline Containers::Array<T> subData(GLintptr offset, GLsizeiptr size);
         #endif
 
         /**

src/Magnum/Framebuffer.h

@@ -359,7 +359,8 @@ class MAGNUM_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractObje
         Framebuffer(const Framebuffer&) = delete;
 
         /** @brief Move constructor */
-        Framebuffer(Framebuffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Framebuffer(Framebuffer&& other) noexcept;
 
         /**
          * @brief Destructor
@@ -373,7 +374,8 @@ class MAGNUM_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractObje
         Framebuffer& operator=(const Framebuffer&) = delete;
 
         /** @brief Move assignment */
-        Framebuffer& operator=(Framebuffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Framebuffer& operator=(Framebuffer&& other) noexcept;
 
         /** @brief OpenGL framebuffer ID */
         GLuint id() const { return _id; }
@@ -386,7 +388,8 @@ class MAGNUM_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractObje
          * equivalent to moved-from state.
          * @see @ref wrap()
          */
-        GLuint release();
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline GLuint release();
 
         #ifndef MAGNUM_TARGET_WEBGL
         /**

src/Magnum/Renderbuffer.h

@@ -129,7 +129,8 @@ class MAGNUM_EXPORT Renderbuffer: public AbstractObject {
         Renderbuffer(const Renderbuffer&) = delete;
 
         /** @brief Move constructor */
-        Renderbuffer(Renderbuffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Renderbuffer(Renderbuffer&& other) noexcept;
 
         /**
          * @brief Destructor
@@ -143,7 +144,8 @@ class MAGNUM_EXPORT Renderbuffer: public AbstractObject {
         Renderbuffer& operator=(const Renderbuffer&) = delete;
 
         /** @brief Move assignment */
-        Renderbuffer& operator=(Renderbuffer&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline Renderbuffer& operator=(Renderbuffer&& other) noexcept;
 
         /** @brief OpenGL renderbuffer ID */
         GLuint id() const { return _id; }
@@ -156,7 +158,8 @@ class MAGNUM_EXPORT Renderbuffer: public AbstractObject {
          * equivalent to moved-from state.
          * @see @ref wrap()
          */
-        GLuint release();
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline GLuint release();
 
         #ifndef MAGNUM_TARGET_WEBGL
         /**

src/Magnum/TransformFeedback.h

@@ -190,7 +190,8 @@ class MAGNUM_EXPORT TransformFeedback: public AbstractObject {
         TransformFeedback(const TransformFeedback&) = delete;
 
         /** @brief Move constructor */
-        TransformFeedback(TransformFeedback&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline TransformFeedback(TransformFeedback&& other) noexcept;
 
         /**
          * @brief Destructor
@@ -204,7 +205,8 @@ class MAGNUM_EXPORT TransformFeedback: public AbstractObject {
         TransformFeedback& operator=(const TransformFeedback&) = delete;
 
         /** @brief Move assignment */
-        TransformFeedback& operator=(TransformFeedback&& other) noexcept;
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline TransformFeedback& operator=(TransformFeedback&& other) noexcept;
 
         /** @brief OpenGL transform feedback ID */
         GLuint id() const { return _id; }
@@ -217,7 +219,8 @@ class MAGNUM_EXPORT TransformFeedback: public AbstractObject {
          * then equivalent to moved-from state.
          * @see @ref wrap()
          */
-        GLuint release();
+        /* MinGW complains loudly if the declaration doesn't also have inline */
+        inline GLuint release();
 
         #ifndef MAGNUM_TARGET_WEBGL
         /**