http: expand http.cookieFile as a path

This should handle .gitconfig files that specify things like:

[http]
	cookieFile = "~/.gitcookies"

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: computersforpeace

Documentation/config.txt

@@ -1598,7 +1598,8 @@ http.proxy::
 	remote.<name>.proxy
 
 http.cookieFile::
-	File containing previously stored cookie lines which should be used
+	The pathname of a file containing previously stored cookie lines,
+	which should be used
 	in the Git http session, if they match the server. The file format
 	of the file to read cookies from should be plain HTTP headers or
 	the Netscape/Mozilla cookie file format (see linkgit:curl[1]).

http.c

@@ -258,7 +258,7 @@ static int http_options(const char *var, const char *value, void *cb)
 		return git_config_string(&curl_http_proxy, var, value);
 
 	if (!strcmp("http.cookiefile", var))
-		return git_config_string(&curl_cookie_file, var, value);
+		return git_config_pathname(&curl_cookie_file, var, value);
 	if (!strcmp("http.savecookies", var)) {
 		curl_save_cookies = git_config_bool(var, value);
 		return 0;