diff_filespec: drop funcname_pattern_ident field

This struct field was obsoleted by be58e70 (diff: unify
external diff and funcname parsing code, 2008-10-05), but we
forgot to remove it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore.h

@@ -29,7 +29,6 @@ struct diff_filespec {
 	char *path;
 	void *data;
 	void *cnt_data;
-	const char *funcname_pattern_ident;
 	unsigned long size;
 	int count;               /* Reference count */
 	int xfrm_flags;		 /* for use by the xfrm */