libtext-charwidth-perl fails to cross build

libtext-charwidth-perl fails to cross-build because perl is not built with the correct cross-config info.

The patched-for-cross version in https://launchpad.net/~linaro-foundations/+archive/cross-alip fails with:

 fakeroot debian/rules clean
Config.pm & Config_heavy.pl for cross building not found in /usr/arm-linux-gnueabi/lib/perl/5.10.1
make: *** [clean] Error 1

Background:
The build command is:
xdeb --only-explicit -a armel --prefer-apt --apt-source --debug --force-rebuild libtext-charwidth-perl

The actual build command xdeb issues is:
debuild --no-lintian -eUSER -eCONFIG_SITE=/etc/dpkg-cross/cross-config.armel -eDEB_BUILD_OPTIONS=nocheck -eGTEST_INCLUDEDIR=/usr/arm-linux-gnueabi/include -eGTEST_LIBDIR=/usr/arm-linux-gnueabi/lib -ePKG_CONFIG_LIBDIR=/usr/arm-linux-gnueabi/lib/pkgconfig:/usr/arm-linux-gnueabi/share/pkgconfig:/usr/share/pkgconfig -eDH_VERBOSE=1 -aarmel -b -uc -us -tc

To easily reproduce the build environment in which this bug was discovered follow the HOWTO here:
https://wiki.linaro.org/Platform/DevPlatform/CrossCompile/CrossBuildNano