Do not unescape unit names in [Install] section

https://bugs.freedesktop.org/show_bug.cgi?id=49316
(cherry picked from commit 000f6e5667)

src/shared/conf-parser.c

@@ -719,7 +719,7 @@ int config_parse_strv(const char *unit,
         FOREACH_WORD_QUOTED(w, l, rvalue, state) {
                 _cleanup_free_ char *n;
 
-                n = cunescape_length(w, l);
+                n = strndup(w, l);
                 if (!n)
                         return log_oom();