crt: Use _UCRT for specifying the CRT to use in certain files

Signed-off-by: Martin Storsjö <martin@martin.st>
diff --git a/mingw-w64-crt/stdio/ucrt_vprintf.c b/mingw-w64-crt/stdio/ucrt_vprintf.c
index 0f7ef28..6f30eef 100644
--- a/mingw-w64-crt/stdio/ucrt_vprintf.c
+++ b/mingw-w64-crt/stdio/ucrt_vprintf.c
@@ -5,7 +5,7 @@
  */
 
 #undef __MSVCRT_VERSION__
-#define __MSVCRT_VERSION__ 0x1400
+#define _UCRT
 #include <stdio.h>
 
 int __cdecl vprintf(const char * __restrict__ _Format,va_list _ArgList)