Fix core Perl module Module::Pluggable such that it can find plugins that live
in symlinked directories.

Patch borrowed/adapted from Nixpkgs.

--- perl-5.16.1/cpan/Module-Pluggable/lib/Module/Pluggable/Object.pm	2015-04-08 23:28:48.120164135 -0500
+++ perl-5.16.1/cpan/Module-Pluggable/lib/Module/Pluggable/Object.pm	2015-04-08 23:30:27.032166704 -0500
@@ -164,7 +164,7 @@
         my $sp = catdir($dir, (split /::/, $searchpath));
 
         # if it doesn't exist or it's not a dir then skip it
-        next unless ( -e $sp && -d _ ); # Use the cached stat the second time
+        next unless ( -e $sp );
 
         my @files = $self->find_files($sp);
 
@@ -279,7 +279,7 @@
                              (my $path = $File::Find::name) =~ s#^\\./##;
                              push @files, $path;
                            }
-                      }, $search_path );
+                      }, "$search_path/." );
     }
     #chdir $cwd;
     return @files;
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<div class='path'>path: <a href='/guix/log/?id=5b4051bf0bba1623f81381fccd680f509c5482ed'>root</a>/<a href='/guix/log/tests?id=5b4051bf0bba1623f81381fccd680f509c5482ed'>tests</a>/<a href='/guix/log/tests/glob.scm?id=5b4051bf0bba1623f81381fccd680f509c5482ed'>glob.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/glob.scm?id=5b4051bf0bba1623f81381fccd680f509c5482ed&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-03-18 22:57:17 +0100'>2018-03-18</span></td><td><a href='/guix/commit/tests/glob.scm?id=71e08fde28fa335bdba2ec2150fd6663390bba5a'>glob: Add an extra glob pattern compilation stage.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/glob.scm (compile-glob-pattern): Rename to...
(string-&gt;sglob): ... this.
(compile-sglob, string-&gt;compiled-sglob): New procedures.
(glob-match?): Replace '?, 'range, and 'set with a single clause.
* tests/glob.scm (test-compile-glob-pattern): Rename to...
(test-string-&gt;sglob): ... this.  Adjust accordingly.
(test-glob-match): Use 'string-&gt;compiled-sglob' instead of
'compile-glob-pattern'.
* gnu/build/linux-modules.scm (read-module-aliases): Use
'string-&gt;compiled-sglob' instead of 'compile-glob-pattern'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-03-18 22:35:36 +0100'>2018-03-18</span></td><td><a href='/guix/commit/tests/glob.scm?id=e914b398af11f909e88a8bc85eeebb0768aacd54'>glob: Support square brackets in patterns.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/glob.scm (wildcard-indices): Remove.
(parse-bracket): New procedure.
(compile-glob-pattern): Rewrite.  Support square brackets for sets and
ranges.
(glob-match?): Support sets and ranges.
* tests/glob.scm (test-compile-glob-pattern)
(test-glob-match): New macros.
Use them to rewrite the existing tests, and add new tests.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-03-02 13:46:25 +0100'>2018-03-02</span></td><td><a href='/guix/commit/tests/glob.scm?id=f14c933df16ee0faee6bff8004da4e5d3e1caf07'>Add (guix glob).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/glob.scm, tests/glob.scm: New files.
* Makefile.am (MODULES): Add guix/glob.scm.
(SCM_TESTS): Add tests/glob.scm.
</span></span></td><td>Ludovic Courtès</td></tr>