configure: remove two more unneeded gtk conditionals
diff --git a/configure.ac b/configure.ac
index f3faaab..189226a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2431,8 +2431,6 @@
 AM_CONDITIONAL(USE_FLITE, false)
 AM_CONDITIONAL(USE_FLUIDSYNTH, false)
 AM_CONDITIONAL(USE_GSM, false)
-AM_CONDITIONAL(USE_GTK3, false)
-AM_CONDITIONAL(USE_GTK3_GL, false)
 AM_CONDITIONAL(USE_HLS, false)
 AM_CONDITIONAL(USE_IQA, false)
 AM_CONDITIONAL(USE_KATE, false)