gnu: perl-tk: Patch for i686

* gnu/packages/patches/perl-tk-x11-discover.patch: New patch.
* gnu-system.am [dist_patch_DATA]: Add it.
* gnu/packages/tcl.scm (perl-tk)[origin]: Use it.

gnu-system.am

@@ -325,6 +325,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/patchelf-page-size.patch			\
   gnu/packages/patches/patchutils-xfail-gendiff-tests.patch	\
   gnu/packages/patches/perl-no-sys-dirs.patch			\
+  gnu/packages/patches/perl-tk-x11-discover.patch		\
   gnu/packages/patches/petsc-fix-threadcomm.patch		\
   gnu/packages/patches/plotutils-libpng-jmpbuf.patch		\
   gnu/packages/patches/procps-make-3.82.patch			\

gnu/packages/patches/perl-tk-x11-discover.patch

+On non-x86_64 systems, this conditional can cause a specified X11 build value
+to be overwritten to null, causing x11 discovery to fail.
+
+--- a/myConfig	2014-05-12 11:16:48.152719722 -0500
++++ b/myConfig	2014-05-12 11:16:24.704719113 -0500
+@@ -350,7 +350,7 @@
+   #
+   # Prefer 64bit libraries on certain architectures
+   #
+-  unless (defined $xlib and $Config{'archname'} =~ m/x86_64/)
++  unless (defined $xlib or not $Config{'archname'} =~ m/x86_64/)
+     {
+       $xlib64 = &lX11(0, chooseX11(</usr/X11*/lib64>));
+     }

gnu/packages/tcl.scm

@@ -23,6 +23,7 @@ (define-module (gnu packages tcl)
   #:use-module (guix download)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system perl)
+  #:use-module (gnu packages)
   #:use-module (gnu packages libpng)
   #:use-module (gnu packages libjpeg)
   #:use-module (gnu packages perl)
@@ -177,7 +178,8 @@ (define-public perl-tk
                    version ".tar.gz"))
              (sha256
               (base32
-               "0jarvplhfvnm0shhdm2a5zczlnk9mkf8jvfjiwyhjrr3cy1gl0w0"))))
+               "0jarvplhfvnm0shhdm2a5zczlnk9mkf8jvfjiwyhjrr3cy1gl0w0"))
+             (patches (list (search-patch "perl-tk-x11-discover.patch")))))
     (build-system perl-build-system)
     (native-inputs `(("pkg-config" ,pkg-config)))
     (inputs `(("libx11" ,libx11)