remote-curl.c: Fix a compiler warning

In particular, gcc issues an "'gzip_size' might be used uninitialized"
warning (-Wuninitialized). However, this warning is a false positive,
since the 'gzip_size' variable would not, in fact, be used uninitialized.
In order to suppress the warning, we simply initialise the variable to
zero in it's declaration.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote-curl.c

@@ -413,7 +413,7 @@ static int post_rpc(struct rpc_state *rpc)
 	struct curl_slist *headers = NULL;
 	int use_gzip = rpc->gzip_request;
 	char *gzip_body = NULL;
-	size_t gzip_size;
+	size_t gzip_size = 0;
 	int err, large_request = 0;
 
 	/* Try to load the entire request, if we can fit it into the