mu: optimize indexing (get_uid_term)

Some users were report seeing get_uid_term high in the profiles; so
optimize this:

- make mu_util_get_hash a static inline function (used by get_uid_term)
- don't use 'realpath' in get_uid_term, seem that's the main culprit
- some slight faster string handling there too.

lib/mu-util.c

@@ -559,25 +559,3 @@ mu_util_read_password (const char *prompt)
 }
 
 
-const char*
-mu_util_get_hash (const char* str)
-{
-	unsigned	djbhash, bkdrhash, bkdrseed;
-	unsigned	u;
-	static char	hex[18];
-
-	g_return_val_if_fail (str, NULL);
-
-	djbhash  = 5381;
-	bkdrhash = 0;
-	bkdrseed = 1313;
-
-	for(u = 0; str[u]; ++u) {
-		djbhash  = ((djbhash << 5) + djbhash) + str[u];
-		bkdrhash = bkdrhash * bkdrseed + str[u];
-	}
-
-	snprintf (hex, sizeof(hex), "%08x%08x", djbhash, bkdrhash);
-
-	return hex;
-}