Hopefully fixed cygwin build problems.

lib/irrlicht/CMakeLists.txt

@@ -570,5 +570,5 @@ if(ENABLE_WAYLAND_DEVICE)
 endif()
 
 if(WIN32)
-    target_link_libraries(stkirrlicht imm32 XINPUT9_1_0.LIB)
+    target_link_libraries(stkirrlicht imm32 XINPUT9_1_0)
 endif()

lib/irrlicht/source/Irrlicht/CIrrDeviceWin32.cpp

@@ -23,8 +23,14 @@
 // This define will switch to use XInput 9.1, which does not
 // require an installer and works on most windows platforms.
 // See https://blogs.msdn.microsoft.com/chuckw/2012/04/25/xinput-and-windows-8/
+#ifdef __CYGWIN__
+#define _WIN32_WINNT 0x0601
+#include <xinput.h>
+#else
+#undef _WIN32_WINNT
 #define _WIN32_WINNT 0x0601
 #include <Xinput.h>
+#endif
 #ifdef _IRR_COMPILE_WITH_DIRECTINPUT_JOYSTICK_
 #define DIRECTINPUT_VERSION 0x0800
 #include <dinput.h>