gpg-interface: make parse_gpg_output static and remove from interface header

Turn parse_gpg_output into a static function, the only outside user was
migrated in an earlier commit.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gpg-interface.c

@@ -35,7 +35,7 @@ static struct {
 	{ 'R', "\n[GNUPG:] REVKEYSIG "},
 };
 
-void parse_gpg_output(struct signature_check *sigc)
+static void parse_gpg_output(struct signature_check *sigc)
 {
 	const char *buf = sigc->gpg_status;
 	int i;

gpg-interface.h

@@ -33,8 +33,6 @@ void signature_check_clear(struct signature_check *sigc);
  */
 size_t parse_signature(const char *buf, size_t size);
 
-void parse_gpg_output(struct signature_check *);
-
 /*
  * Create a detached signature for the contents of "buffer" and append
  * it after "signature"; "buffer" and "signature" can be the same