[BUGFIX] PHP Module pgsql not supported

On some systems (e.g. current Debian system) the module for PostgreSQL is
called pgsql instead of postgres. So this has to be added to the module
list.

Change-Id: Id55170cefef6df32ae616c05696bec8fa59b9cb2
Fixes: #43163
Releases: 6.0, 4.7, 4.5
Reviewed-on: https://review.typo3.org/21089
Reviewed-by: Stefan Neufeind
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert