I copied these two files and two links from the version 2.8 download (http://files.ampps.com/AMPPS-2.8.dmg). Not sure if this is ideal, but my php -m is now "clean."
iMac:lib pnosko$ cd /Volumes/AMPPS/AMPPS/extra/lib
iMac:lib pnosko$ ls -l libpq*
-rwxr-xr-x 1 pnosko staff 142636 Dec 24 07:48 libpq.5.6.dylib
lrwxr-xr-x 1 pnosko staff 15 Dec 31 07:19 libpq.5.dylib -> libpq.5.6.dylib
-rw-r--r-- 1 pnosko staff 185400 Dec 24 07:48 libpq.a
lrwxr-xr-x 1 pnosko staff 15 Dec 31 07:19 libpq.dylib -> libpq.5.6.dylib