Removed Buffer::maxVertexAttributeBindings().

This queries limit for ARB_vertex_attrib_binding extension, which isn't
and probably won't be implemented in near future.

doc/opengl-mapping.dox

@@ -343,7 +343,7 @@ OpenGL function                        | Matching API
 @def_gl{MAX_UNIFORM_BUFFER_BINDINGS}   | @ref Buffer::maxUniformBindings()
 @def_gl{MAX_UNIFORM_LOCATIONS}         | @ref AbstractShaderProgram::maxUniformLocations()
 @def_gl{MAX_VERTEX_ATTRIBS}            | @ref AbstractShaderProgram::maxVertexAttributes()
-@def_gl{MAX_VERTEX_ATTRIB_BINDINGS}    | @ref Buffer::maxVertexAttributeBindings()
+@def_gl{MAX_VERTEX_ATTRIB_BINDINGS}    | |
 @def_gl{MAX_VERTEX_ATTRIB_RELATIVE_OFFSET} | |
 @def_gl{MAX_VIEWPORTS}                 | |
 @def_gl{MAX_VIEWPORT_DIMS}             | @ref AbstractFramebuffer::maxViewportSize()

src/Magnum/Buffer.h

@@ -479,15 +479,6 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
         static Int maxUniformBindings();
         #endif
 
-        /**
-         * @brief Max supported vertex buffer binding count
-         *
-         * The result is cached, repeated queries don't result in repeated
-         * OpenGL calls.
-         * @see @fn_gl{Get} with @def_gl{MAX_VERTEX_ATTRIB_BINDINGS}
-         */
-        static Int maxVertexAttributeBindings();
-
         /**
          * @brief Unbind any buffer from given target
          * @param target    %Target