Merge pull request #1551 from Crunkle/master

Fix incorrect header name on Linux MinGW systems.

imgui.cpp

@@ -11524,7 +11524,11 @@ void ImGui::EndDragDropTarget()
 #if defined(_WIN32) && !defined(_WINDOWS_) && (!defined(IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCTIONS) || !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS))
 #undef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
+#ifndef __MINGW32__
 #include <Windows.h>
+#else
+#include <windows.h>
+#endif
 #endif
 
 // Win32 API clipboard implementation