MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).
Remove the other user-visible ABI: signal handling. This code
should basically have been inactive after the prctl()s were
removed, but there may be some small ABI remnants from this code.
Remove it.
Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: x86@kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>