include: SwitchToThread is always available on Win10

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

mingw-w64-headers/include/processthreadsapi.h

diff --git a/mingw-w64-headers/include/processthreadsapi.h b/mingw-w64-headers/include/processthreadsapi.h
index 7e14eb9..c4629f7 100755
--- a/mingw-w64-headers/include/processthreadsapi.h
+++ b/mingw-w64-headers/include/processthreadsapi.h
@@ -167,6 +167,7 @@
   WINBASEAPI WINBOOL WINAPI GetExitCodeThread (HANDLE hThread, LPDWORD lpExitCode);
 #if _WIN32_WINNT >= 0x0A00
   WINBASEAPI DWORD WINAPI QueueUserAPC (PAPCFUNC pfnAPC, HANDLE hThread, ULONG_PTR dwData);
+  WINBASEAPI WINBOOL WINAPI SwitchToThread (VOID);
 #endif
   WINBASEAPI DWORD WINAPI SuspendThread (HANDLE hThread);
   WINBASEAPI DWORD WINAPI ResumeThread (HANDLE hThread);