This adds --enable-poppler configure option.
Poppler can be enabled/disabled by setting this
parameter to yes or no.

Change-Id: I42ba2d27de7b5014d28523394310616d20073b71
Reviewed-on: https://gerrit.libreoffice.org/68602Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/68842
Tested-by: Jenkins