Revert "sigchain: add wrappers for sigaction64/sigprocmask64."

This reverts commit eb4640badb740f719bda33439ce9ae1953fb6a4c.

Reason for revert: breaks mac builds.

Change-Id: I4b80a997e0580bd3a20dfb427a6e83cf0c2b2d47
6 files changed