configure.in: edit message checking for new GStreamer 1.0
configure.in: edit message checking for new GStreamer 1.0

to not duplicate the message checking for old one
and be consistent with the help message in AS_HELP_STRING

Change-Id: I91e0a5ed0e2278de013d7872eadc6f93b970c231
Reviewed-on: https://gerrit.libreoffice.org/722
Reviewed-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>
Tested-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core