$docdev fixups: mostly to avoid empty output

... after auto-removing some kinds of files by default.
In some cases I let them be removed and in others I let them be put into
$docdev. That was more due to general indecisiveness on this question
than any reasons in the particular cases.

pkgs/development/perl-modules/generic/builder.sh

@@ -28,12 +28,6 @@ preConfigure() {
     perl Makefile.PL PREFIX=$out INSTALLDIRS=site $makeMakerFlags
 }
 
-preFixup() {
-    if [ -n "$man" ]; then
-        mkdir -p $man/share
-        if [ -d $out/man ]; then mv $out/man $man/share/; fi
-    fi
-}
 
 postFixup() {
     # If a user installs a Perl package, she probably also wants its