Hi all,

As per https://gcc.gnu.org/ml/gcc-patches/2015-05/msg01166.html
I saw that STACK_GROWS_DOWNWARD is being checked for ifdef in a number of places
unrelated to the patch in the PR, so decided to remove the ifdef checks for STACK_GROWS_DOWNWARD
in a separate patch. It's fairly mechanical.

Bootstrapped on x86_64 and aarch64 and tested on arm.
I believe these patches are considered obvious, so I'll commit this in a day, unless someone objects,
before proceeding with the changes in https://gcc.gnu.org/ml/gcc-patches/2015-05/msg01166.html

2015-05-18  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * calls.c: Always define STACK_GROWS_DOWNWARD as 0 or 1.
     (mem_overlaps_already_clobbered_arg_p): Rewrite ifdef
     STACK_GROWS_DOWNWARD as normal if.
     (expand_call): Likewise.