Update configure.ac

Run autoupdate
Add AM_PROG_AR

/usr/share/automake-1.14/am/ltlibrary.am: warning: 'libcommon.la': linking libtool libraries using a non-POSIX
/usr/share/automake-1.14/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'
src/common/Makefile.am:16:   while processing Libtool library 'libcommon.la'
Update ax_pthread.m4

The macro has a new name