cpan_build bbclass: do not install module into /usr/share

cpan_build bbclass: do not install module into /usr/share

https://github.com/openembedded/oe-core/commit/83796edd29561f02b6f7b036351711f8def77a4f is a partial solution, this fixes cpan_build.bbclass as well.

A non-working one looks like this:
	[koen@rrmbp v2013.06]$ dpkg-deb -c deploy/eglibc/ipk/armv7ahf-vfp-neon/perl-module-build-withxspp_0.14-r0.0_armv7ahf-vfp-neon.ipk
	-rw-r--r-- root/root       361 2013-11-28 16:50 ./usr/lib/perl/auto/Module/Build/WithXSpp/.packlist
	-r--r--r-- root/root     22557 2013-11-28 16:50 ./usr/share/perl/Module/Build/WithXSpp.pm

It now looks like this:
	[koen@rrmbp v2013.06]$ dpkg-deb -c deploy/eglibc/ipk/armv7ahf-vfp-neon/perl-module-build-withxspp_0.14-r*.ipk
	-rw-r--r-- root/root       378 2013-11-29 14:44 ./usr/lib/perl/auto/Module/Build/WithXSpp/.packlist
	-r--r--r-- root/root     22557 2013-11-28 17:22 ./usr/lib/perl/vendor_perl/5.14.3/Module/Build/WithXSpp.pm

(From OE-Core rev: 1bfcbdbe15bf5a0fce4cb3acb63ae86d98d56277)

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>