/*
 * If /x was used, we have to worry about a regex
 * ending with a comment later being embedded
 * within another regex. If so, we don't want this
 * regex's "commentization" to leak out to the
 * right part of the enclosing regex, we must cap
 * it with a newline.
 *
 * So, if /x was used, we scan backwards from the
 * end of the regex. If we find a '#' before we
 * find a newline, we need to add a newline
 * ourself. If we find a '\n' first (or if we
 * don't find '#' or '\n'), we don't need to add
 * anything.  -jfriedl
 */