Albert Astals Cid points out that --disable-libjpeg causes poppler to
use internal JPEG code instead, which is not actively maintained.

Add LIBJPEG_CFLAGS / LIBJPEG_LIBS to config_host.mk and patch poppler to
respect LIBJPEG_LIBS.

Change-Id: Id19a62a9bd9dc41fee5e8e43e2798e515aacc299
Reviewed-on: https://gerrit.libreoffice.org/30496Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>