Log Message:
We don't actually want everything to be built with pthreads -- only
libldap_r and slurpd.  Patch those Makefiles (patch-aj, patch-ak) to
pass $(PTHREAD_CFLAGS) and $(PTHREAD_LDFLAGS) to the build.  The
configure process correctly adds any necessary libraries, so adding
$(PTHREAD_LIBS) isn't needed.  Bump the PKGREVISION since the LDAP
libraries are no longer linked against libpthread.

This fixes PR pkg/28259.