Log Message:
libsigsegv: update to 2.12.

New in 2.12:

* Added support for catching stack overflow on Hurd/i386.

* Added support for catching stack overflow on Haiku.

* Corrected distinction between stack overflow and other fault on AIX.

* Reliability improvements on Linux, FreeBSD, NetBSD.

* NOTE: Support for Cygwin and native Windows is currently not up-to-date.