pinentry: remove non-existent configure options for Qt3 and GTK+1

Qt3 and GTK+1 support were removed by this commit:
  http://git.gnupg.org/cgi-bin/gitweb.cgi?p=pinentry.git;a=commit;h=f2ed42297528f2a126d189c6181d3105ceecca22



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>