These two variables are used by more than just the linker;
they're also used by head.S to know where it can safely
place the page tables.  We therefore need to export it
from the Makefile.

These are also highly machine dependent; we don't want
to duplicate the same set of conditionals for cpp and
for the makefiles.

arch/arm/Makefile also contained a stray close-paren.  I'm
submitting this one to the lost property office.

We also always pass -mno-fpu to the assember; this
guarantees that any floating point will be caught.