from git://git.savannah.gnu.org/autoconf-archive.git
100644 blob d383ad5c6d m4/ax_pthread.m4
dd94691 AX_PTHREAD: add support for Clang
386b290 AX_PTHREAD: fix support for AIX
e40cfd6 AX_PTHREAD: improve support for AIX
Change-Id: Ic1f1edc656e4e917b88f151493147f650b94242f