snapshot: support special value 'all' to enable all formats

Signed-off-by: Christian Hesse <mail@eworm.de>
Reviewed-by: John Keeping <john@keeping.me.uk>

cgitrc.5.txt

@@ -429,6 +429,7 @@ snapshots::
 	Text which specifies the default set of snapshot formats that cgit
 	generates links for. The value is a space-separated list of zero or
 	more of the values "tar", "tar.gz", "tar.bz2", "tar.xz" and "zip".
+	The special value "all" enables all snapshot formats.
 	Default value: none.
 
 source-filter::

shared.c

@@ -390,6 +390,9 @@ int cgit_parse_snapshots_mask(const char *str)
 	if (atoi(str))
 		return 1;
 
+	if (strcmp(str, "all") == 0)
+		return INT_MAX;
+
 	string_list_split(&tokens, str, ' ', -1);
 	string_list_remove_empty_items(&tokens, 0);