msvcrt: Copy memcmp implementation from ntdll.

dlls/msvcrt/string.c

@@ -2219,7 +2219,14 @@ int CDECL MSVCRT_I10_OUTPUT(MSVCRT__LDOUBLE ld80, int prec, int flag, struct _I1
  */
 int __cdecl MSVCRT_memcmp(const void *ptr1, const void *ptr2, MSVCRT_size_t n)
 {
-    return memcmp(ptr1, ptr2, n);
+    const unsigned char *p1, *p2;
+
+    for (p1 = ptr1, p2 = ptr2; n; n--, p1++, p2++)
+    {
+        if (*p1 < *p2) return -1;
+        if (*p1 > *p2) return 1;
+    }
+    return 0;
 }
 
 /*********************************************************************