gplugin/gplugin

add additional search directories to find libperl (fixes issue that libperl is not found on openSUSE)

Testing Done:
built on openSUSE and Gentoo

Reviewed at https://reviews.imfreedom.org/r/851/
if get_option('nls')
i18n.gettext(GETTEXT_PACKAGE)
else
summary('translations',
'You have disabled installation of translations which means ' +
'English will be the only available language.',
section : 'Warnings')
endif