lang/gcc6-aux: Remove useless ARMv6 patch

By Makefile restriction, gcc6-aux can only be built on x86-64 and i386.
This restriction is due to a lack of a bootstrap compiler required for
Ada. Thus, the recently added ARMv6 patch has no effect (plus gcc6-aux
is updated by diff-* patchsets and single patches can interfer with
that scheme.)