wikiheaders: Man pages should escape apostrophe chars.

This prevents problems if one starts a line, which would cause it to be
interpreted as a command character.

Fixes #13038.

build-scripts/wikiheaders.pl

@@ -426,6 +426,7 @@ sub dewikify_chunk {
         # make sure these can't become part of roff syntax.
         $str =~ s/\./\\[char46]/gms;
         $str =~ s/"/\\(dq/gms;
+        $str =~ s/'/\\(aq/gms;
 
         if ($wikitype eq 'mediawiki') {
             # Dump obvious wikilinks.