drop some obsolete "x = x" compiler warning hacks

In cases where the setting and access of a variable are
protected by the same conditional flag, older versions of
gcc would generate a "might be used unitialized" warning. We
silence the warning by initializing the variable to itself,
a hack that gcc recognizes.

Modern versions of gcc are smart enough to get this right,
going back to at least version 4.3.5. gcc 4.1 does get it
wrong in both cases, but is sufficiently old that we
probably don't need to care about it anymore.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/cat-file.c

@@ -193,7 +193,7 @@ static int batch_one_object(const char *obj_name, int print_contents)
 	unsigned char sha1[20];
 	enum object_type type = 0;
 	unsigned long size;
-	void *contents = contents;
+	void *contents;
 
 	if (!obj_name)
 	   return 1;

fast-import.c

@@ -2434,7 +2434,7 @@ static void note_change_n(struct branch *b, unsigned char *old_fanout)
 {
 	const char *p = command_buf.buf + 2;
 	static struct strbuf uq = STRBUF_INIT;
-	struct object_entry *oe = oe;
+	struct object_entry *oe;
 	struct branch *s;
 	unsigned char sha1[20], commit_sha1[20];
 	char path[60];