include: Add wmemcpy to wchar.h.

include/msvcrt/wchar.h

@@ -10,6 +10,7 @@
 
 #include <crtdefs.h>
 #include <stdarg.h>
+#include <string.h>
 
 #include <pshpack8.h>
 
@@ -495,6 +496,11 @@ static inline int wmemcmp(const wchar_t *s1, const wchar_t *s2, size_t n)
     return 0;
 }
 
+static inline wchar_t* __cdecl wmemcpy(wchar_t *dst, const wchar_t *src, size_t n)
+{
+    return memcpy(dst, src, n * sizeof(wchar_t));
+}
+
 #ifdef __cplusplus
 }
 #endif