Disallow use of undocumented snapshot delimiters

Since the introduction of selective snapshot format configuration in
dc3c9b5 (allow selective enabling of snapshots, 2007-07-21), we allowed
seven different delimiters for snapshot formats, while the documentation
has always been clear about spaces being the only valid delimiter:

    The value is a space-separated list of zero or more of the values
    "tar", "tar.gz", "tar.bz2", "tar.xz" and "zip".

Supporting the undocumented delimiters makes the code unnecessarily
complex. Remove them.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

shared.c

@@ -405,7 +405,7 @@ void cgit_diff_commit(struct commit *commit, filepair_fn fn, const char *prefix)
 int cgit_parse_snapshots_mask(const char *str)
 {
 	const struct cgit_snapshot_format *f;
-	static const char *delim = " \t,:/|;";
+	static const char *delim = " ";
 	int tl, sl, rv = 0;
 
 	/* favor legacy setting */