Added missing winmm loading errors.

README.md

@@ -49,6 +49,8 @@ The following dependencies are needed by the examples and test programs:
  - Added `glfwSetDropCallback` and `GLFWdropfun` for receiving dropped files
  - [Cocoa] Bugfix: Using a 1x1 cursor for hidden mode caused some screen
                    recorders to fail
+ - [Win32] Bugfix: Failure to load winmm or its functions was not reported to
+                   the error callback
  - [X11] Bugfix: The case of finding no usable CRTCs was not detected
  - [X11] Bugfix: Detection of broken Nvidia RandR gamma support did not verify
                  that at least one CRTC was present

src/win32_init.c

@@ -65,7 +65,11 @@ static GLboolean initLibraries(void)
 
     _glfw.win32.winmm.instance = LoadLibrary(L"winmm.dll");
     if (!_glfw.win32.winmm.instance)
+    {
+        _glfwInputError(GLFW_PLATFORM_ERROR,
+                        "Win32: Failed to load winmm.dll");
         return GL_FALSE;
+    }
 
     _glfw.win32.winmm.joyGetDevCaps = (JOYGETDEVCAPS_T)
         GetProcAddress(_glfw.win32.winmm.instance, "joyGetDevCapsW");
@@ -81,6 +85,8 @@ static GLboolean initLibraries(void)
         !_glfw.win32.winmm.joyGetPosEx ||
         !_glfw.win32.winmm.timeGetTime)
     {
+        _glfwInputError(GLFW_PLATFORM_ERROR,
+                        "Win32: Failed to load winmm functions");
         return GL_FALSE;
     }
 #endif // _GLFW_NO_DLOAD_WINMM