ITS#9525 - Rework contrib module builds

Adjust to honor CFLAGS and LDFLAGS
Drop -Wall from the OPTimization flag
3 jobs for master in 60 minutes and 2 seconds (queued for 2 minutes and 43 seconds)
Status Name Job ID Coverage
  Build
passed build-gnutls-mit-standalone-lloadd #6537

00:51:01

passed build-no-threads-no-slapd #6535

00:03:17

passed build-openssl-heimdal-lloadd #6536

00:51:08