[win32] suppress false warning by mingw gcc

vsnprintf.c

@@ -561,7 +561,7 @@ BSD_vfprintf(FILE *fp, const char *fmt0, va_list ap)
 	int fprec = 0;		/* floating point precision */
 	char expstr[7];		/* buffer for exponent string */
 #endif
-	u_long MAYBE_UNUSED(ulval); /* integer arguments %[diouxX] */
+	u_long MAYBE_UNUSED(ulval) = 0; /* integer arguments %[diouxX] */
 #ifdef _HAVE_SANE_QUAD_
 	u_quad_t MAYBE_UNUSED(uqval); /* %q integers */
 #endif /* _HAVE_SANE_QUAD_ */

win32/win32.c

@@ -5271,7 +5271,7 @@ static int
 wrename(const WCHAR *oldpath, const WCHAR *newpath)
 {
     int res = 0;
-    DWORD oldatts, newatts = (DWORD)-1;
+    DWORD oldatts = 0, newatts = (DWORD)-1;
     DWORD oldvsn = 0, newvsn = 0, e;
 
     e = get_attr_vsn(oldpath, &oldatts, &oldvsn);