Win32: Remove support for original MinGW

The original MinGW distribution appears to no longer be maintained and
should not be used.  Anyone still using MinGW should consider switching
to the MinGW-w64 fork or another actively maintained toolchain.
MinGW-w64 supports 64-bit binaries and provides much newer compilers and
Win32 headers.

Fixes #2540

src/CMakeLists.txt

@@ -255,24 +255,6 @@ if (GLFW_BUILD_WIN32)
     target_compile_definitions(glfw PRIVATE UNICODE _UNICODE)
 endif()
 
-# HACK: When building on MinGW, WINVER and UNICODE need to be defined before
-# the inclusion of stddef.h (by glfw3.h), which is itself included before
-# win32_platform.h.  We define them here until a saner solution can be found
-# NOTE: MinGW-w64 and Visual C++ do /not/ need this hack.
-if (MINGW)
-    target_compile_definitions(glfw PRIVATE WINVER=0x0501)
-endif()
-
-# Workaround for legacy MinGW not providing XInput and DirectInput
-if (MINGW)
-    include(CheckIncludeFile)
-    check_include_file(dinput.h DINPUT_H_FOUND)
-    check_include_file(xinput.h XINPUT_H_FOUND)
-    if (NOT DINPUT_H_FOUND OR NOT XINPUT_H_FOUND)
-        target_include_directories(glfw PRIVATE "${GLFW_SOURCE_DIR}/deps/mingw")
-    endif()
-endif()
-
 # Workaround for the MS CRT deprecating parts of the standard library
 if (MSVC OR CMAKE_C_SIMULATE_ID STREQUAL "MSVC")
     target_compile_definitions(glfw PRIVATE _CRT_SECURE_NO_WARNINGS)
@@ -286,10 +268,6 @@ endif()
 if (GLFW_BUILD_SHARED_LIBRARY)
     if (WIN32)
         if (MINGW)
-            # Remove the dependency on the shared version of libgcc
-            # NOTE: MinGW-w64 has the correct default but MinGW needs this
-            target_link_libraries(glfw PRIVATE "-static-libgcc")
-
             # Remove the lib prefix on the DLL (but not the import library)
             set_target_properties(glfw PROPERTIES PREFIX "")
 

src/platform.c

@@ -187,8 +187,6 @@ GLFWAPI const char* glfwGetVersionString(void)
         " OSMesa"
 #if defined(__MINGW64_VERSION_MAJOR)
         " MinGW-w64"
-#elif defined(__MINGW32__)
-        " MinGW"
 #elif defined(_MSC_VER)
         " VisualC"
 #endif

src/win32_platform.h

@@ -83,24 +83,12 @@
 #ifndef WM_COPYGLOBALDATA
  #define WM_COPYGLOBALDATA 0x0049
 #endif
-#ifndef WM_UNICHAR
- #define WM_UNICHAR 0x0109
-#endif
-#ifndef UNICODE_NOCHAR
- #define UNICODE_NOCHAR 0xFFFF
-#endif
 #ifndef WM_DPICHANGED
  #define WM_DPICHANGED 0x02E0
 #endif
-#ifndef GET_XBUTTON_WPARAM
- #define GET_XBUTTON_WPARAM(w) (HIWORD(w))
-#endif
 #ifndef EDS_ROTATEDMODE
  #define EDS_ROTATEDMODE 0x00000004
 #endif
-#ifndef DISPLAY_DEVICE_ACTIVE
- #define DISPLAY_DEVICE_ACTIVE 0x00000001
-#endif
 #ifndef _WIN32_WINNT_WINBLUE
  #define _WIN32_WINNT_WINBLUE 0x0603
 #endif
@@ -113,9 +101,6 @@
 #ifndef USER_DEFAULT_SCREEN_DPI
  #define USER_DEFAULT_SCREEN_DPI 96
 #endif
-#ifndef OCR_HAND
- #define OCR_HAND 32649
-#endif
 
 #if WINVER < 0x0601
 typedef struct