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

Patch borrowed/adapted from Nixpkgs.

--- Module-Pluggable-5.2/lib/Module/Pluggable/Object.pm   2015-04-08 23:28:48.120164135 -0500
+++ Module-Pluggable-5.2/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;ss='sub right'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>root</a>/<a href='/guix/log/tests?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>tests</a>/<a href='/guix/log/tests/zlib.scm?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>zlib.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/zlib.scm?id=afb82831fa4d8602859eb00056dd3f418ed363c9&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-10-11 15:20:50 +0200'>2017-10-11</span></td><td><a href='/guix/commit/tests/zlib.scm?id=85a2b58987bc32e33e63bea86c1a94496b796ae9'>zlib: Fix memory leak due to revealed ports not being GC'd.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/28784&gt;.

This mostly reverts 81a0f1cdf12e7bcc34c1203f034a323fa8f52cf5, which
introduced a regression: revealed ports are *never* GC'd (contrary to
what Guile's manual suggests).

In addition to the revert, 'close-procedure' now explicitly swallows
EBADF errors when 'close-port' is called.

* guix/zlib.scm (close-procedure): New procedure.
(make-gzip-input-port)[gzfile]: Use 'fileno' instead of 'port-&gt;fdes'.
Use 'close-procedure' instead of 'gzclose'.
(make-gzip-output-port): Likewise.
* tests/zlib.scm ("compression/decompression pipe"): Use 'port-closed?'
to determine whether PARENT has been closed.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-03-15 15:19:53 +0100'>2017-03-15</span></td><td><a href='/guix/commit/tests/zlib.scm?id=81a0f1cdf12e7bcc34c1203f034a323fa8f52cf5'>zlib: Don't rely on EBADF being ignored by 'fport_close'.</a><span class='msg-avail'>...<span class='msg-tooltip'>In 2.2, 'fport_close' no longer swallows EBADF and instead raises a
'system-error' for this.  This commit adjusts for 2.2.

* guix/zlib.scm (close-procedure): Remove.
(make-gzip-input-port): Use 'port-&gt;fdes' instead of 'fileno'.
Use 'gzclose' instead of 'close-procedure'.
(make-gzip-output-port): Likewise.
* tests/zlib.scm ("compression/decompression pipe"): Don't check whether
PARENT is closed using 'port-closed?'.  Instead, use 'seek' on the
underlying FD and check for EBADF.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-07-19 00:07:12 +0200'>2016-07-19</span></td><td><a href='/guix/commit/tests/zlib.scm?id=721539026dda02e58addbb618f2102b31a2927f8'>Add (guix zlib).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/zlib.scm, tests/zlib.scm: New files.
* Makefile.am (MODULES): Add guix/zlib.scm.
(SCM_TESTS): Add tests/zlib.scm.
* m4/guix.m4 (GUIX_LIBGCRYPT_LIBDIR): New macro.
* configure.ac (LIBGCRYPT_LIBDIR): Use it.  Define and substitute
'LIBZ'.
* guix/config.scm.in (%libz): New variable.
</span></span></td><td>Ludovic Courtès</td></tr>