crt: Silence warnings when building _*wc_nolock

Define a high enough version for __MSVCRT_VERSION__ to make the
declarations visible.

These started warning about implicit definitions since
2f9a13461d265592b33cc9ff0e425ecb0df9499c.

Signed-off-by: Martin Storsjö <martin@martin.st>

mingw-w64-crt/stdio/_getwc_nolock.c

diff --git a/mingw-w64-crt/stdio/_getwc_nolock.c b/mingw-w64-crt/stdio/_getwc_nolock.c
index 1d79602..fba41ca 100644
--- a/mingw-w64-crt/stdio/_getwc_nolock.c
+++ b/mingw-w64-crt/stdio/_getwc_nolock.c
@@ -1,3 +1,5 @@
+#undef __MSVCRT_VERSION__
+#define __MSVCRT_VERSION__ 0x800
 #include <stdio.h>
 
 #undef _getwc_nolock

mingw-w64-crt/stdio/_putwc_nolock.c

diff --git a/mingw-w64-crt/stdio/_putwc_nolock.c b/mingw-w64-crt/stdio/_putwc_nolock.c
index 77fe8fd..44da19f 100644
--- a/mingw-w64-crt/stdio/_putwc_nolock.c
+++ b/mingw-w64-crt/stdio/_putwc_nolock.c
@@ -1,3 +1,5 @@
+#undef __MSVCRT_VERSION__
+#define __MSVCRT_VERSION__ 0x800
 #include <stdio.h>
 
 #undef _putwc_nolock