Merge branch 'maint'

* maint:
  parse-options: fix clang opterror() -Wunused-value warning

Author: gitster

parse-options.h

@@ -180,7 +180,7 @@ extern NORETURN void usage_msg_opt(const char *msg,
 
 extern int optbug(const struct option *opt, const char *reason);
 extern int opterror(const struct option *opt, const char *reason, int flags);
-#if defined(__GNUC__) && ! defined(clang)
+#if defined(__GNUC__) && ! defined(__clang__)
 #define opterror(o,r,f) (opterror((o),(r),(f)), -1)
 #endif