Revert "nmsg/isc/Makefile.am: don't install pb-c.h headers"
Revert "nmsg/isc/Makefile.am: don't install pb-c.h headers"

This reverts commit 9d619cec686a6e50634b297a190c10690c306d5d.

hstern/nmsg,hstern/nmsg,hstern/nmsg,hstern/nmsg,hstern/nmsg