MinGW: Scan for \r in addition to \n when reading shbang lines

\r is common on Windows, so we should handle it gracefully.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.c

@@ -525,8 +525,8 @@ static const char *parse_interpreter(const char *cmd)
 	if (buf[0] != '#' || buf[1] != '!')
 		return NULL;
 	buf[n] = '\0';
-	p = strchr(buf, '\n');
-	if (!p)
+	p = buf + strcspn(buf, "\r\n");
+	if (!*p)
 		return NULL;
 
 	*p = '\0';