Platform: add #ifdefs in GlfwApplication.

Window size limits were added in GLFW 3.2,so we make it visible only in
that case.

src/Magnum/Platform/GlfwApplication.cpp

@@ -534,6 +534,7 @@ Vector2i GlfwApplication::windowSize() const {
     return size;
 }
 
+#if (GLFW_VERSION_MAJOR*100 + GLFW_VERSION_MINOR >= 302)
 void GlfwApplication::setMinWindowSize(const Vector2i& size) {
     CORRADE_ASSERT(_window, "Platform::GlfwApplication::setMinWindowSize(): no window opened", );
 
@@ -547,6 +548,7 @@ void GlfwApplication::setMaxWindowSize(const Vector2i& size) {
     glfwSetWindowSizeLimits(_window, _minWindowSize.x(), _minWindowSize.y(), size.x(), size.y());
     _maxWindowSize = size;
 }
+#endif
 
 #ifdef MAGNUM_TARGET_GL
 Vector2i GlfwApplication::framebufferSize() const {

src/Magnum/Platform/GlfwApplication.h

@@ -336,11 +336,14 @@ class GlfwApplication {
          */
         Vector2i windowSize() const;
 
+        #if (GLFW_VERSION_MAJOR*100 + GLFW_VERSION_MINOR >= 302) || defined(DOXYGEN_GENERATING_OUTPUT)
         /**
          * @brief Set window minimum size
          * @param size    The minimum size, in screen coordinates.
          * 
          * If a value is set to -1, it will disable/remove the corresponding limit.
+         * 
+         * @note Supported since GLFW 3.2.
          */
         void setMinWindowSize(const Vector2i& size = {-1, -1});
         
@@ -349,8 +352,11 @@ class GlfwApplication {
          * @param size    The maximum size, in screen coordinates.
          * 
          * If a value is set to -1, it will disable/remove the corresponding limit.
+         *
+         * @note Supported since GLFW 3.2.
          */
         void setMaxWindowSize(const Vector2i& size = {-1, -1});
+        #endif
 
         #if defined(MAGNUM_TARGET_GL) || defined(DOXYGEN_GENERATING_OUTPUT)
         /**