perl: Don't link against libnsl, fix PPC signedness

perl: Don't try to link against libnsl

And also remove all other references to avoid confusion.
libnsl isn't really needed. Removing it allows glibc based
toolchains to build perl.

perl: Make I8/I16/I32 types explicitly signed for PPC

Type signedness is undefined for char. char may actually be unsigned for
some CPUs.
This fixes various bugs on PPC, like negative array indices.

Signed-off-by: Marcel Denia <naoir@gmx.net>