Start to disallow llvm.frameaddress and llvm.returnaddress in ABI checker.

Start to disallow llvm.frameaddress and llvm.returnaddress in ABI checker.

They do not seem to be widely used by user code.

* The boehm garbage collector library does reference
__builtin_return_address under an ifdef, but it
does not appear to be compiled in.

* Mesa-7.6 uses __builtin_frame_address
for u_debug_stack.c, but that also does not appear to be
part of the built libraries.

They expose stack/code addresses (at least the lower
32-bits of the address).

As part of https://codereview.chromium.org/14619022/,
we stopped considering the scons and gcc torture tests that
use these intrinsics as meeting the stable ABI.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3378
R=dschuff@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-llvm.git;a=commit;h=33da0d9

[Derek Schuff, 2013-05-10 22:36:10]

lgtm

[jvoung (off chromium), 2013-05-14 00:07:36]

Committed patchset #3 manually as r33da0d9 (presubmit successful).