Merge branch 'rs/mingw-tighten-mkstemp' into maint

mkstemp() emulation on Windows has been improved.
source: <7265e37f-fd29-3579-b840-19a1df52a59f@web.de>

* rs/mingw-tighten-mkstemp:
  mingw: avoid mktemp() in mkstemp() implementation

compat/mingw.c

@@ -1059,10 +1059,7 @@ char *mingw_mktemp(char *template)
 
 int mkstemp(char *template)
 {
-	char *filename = mktemp(template);
-	if (!filename)
-		return -1;
-	return open(filename, O_RDWR | O_CREAT, 0600);
+	return git_mkstemp_mode(template, 0600);
 }
 
 int gettimeofday(struct timeval *tv, void *tz)