Trac #22505: perl_term_readline_gnu fails to install

The package `perl_term_readline_gnu` fails to install on archlinux with
gcc 6.3.1. See the attached [https://trac.sagemath.org/attachment/ticket
/22505/perl_term_readline_gnu-1.34.log perl_term_readline_gnu-1.34.log].

(note: I do have everything I need on my system and disabling the
installation just make everything else works)

URL: https://trac.sagemath.org/22505
Reported by: vdelecroix
Ticket author(s): Matthias Koeppe
Reviewer(s): Vincent Delecroix

build/pkgs/perl_term_readline_gnu/spkg-install

@@ -8,5 +8,10 @@ fi
 
 cd src
 
-perl Makefile.PL --prefix=$SAGE_LOCAL INSTALL_BASE=$SAGE_LOCAL
+# In the configure phase, the package fails to use rpath for a test
+# program that it compiles, causing a build failure on Linux as
+# reported in #22505 (libreadline.so not found).  We work around it by
+# using LD_LIBRARY_PATH.
+export LD_LIBRARY_PATH="$SAGE_LOCAL/lib":"$LD_LIBRARY_PATH"
+perl Makefile.PL --prefix="$SAGE_LOCAL" INSTALL_BASE="$SAGE_LOCAL"
 $MAKE install