Fix gcc mkspec being considered incompatible

Fix Gcc mkspec for linux-g++-32 being considered incompatible with
linux-g++ on 32 bit machines (and same for 64bit ones).

Change-Id: Iaf914f26e0aed298ff5a875b5e3af3735d4142d9
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>