Set allow_screen_content_tools to 0 in rt mode

Make sure allow_screen_content_tools is 0 in real-time mode, even when
reduced_still_picture_hdr is 1 (which causes force_screen_content_tools
to be set to 2).

BUG=aomedia:2833

Change-Id: I17ad9361a341c5c6d06770ab4d8bd9d4cfcc9dfe
(cherry picked from commit e53999055e9fc95d5cedeb582de7809464d69fe9)

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 6c1fb2c..6f8774b9 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -4001,6 +4001,12 @@
     return;
   }
 
+  if (cpi->oxcf.mode == REALTIME) {
+    assert(cm->seq_params.reduced_still_picture_hdr);
+    features->allow_screen_content_tools = features->allow_intrabc = 0;
+    return;
+  }
+
   if (cpi->oxcf.content == AOM_CONTENT_SCREEN) {
     features->allow_screen_content_tools = features->allow_intrabc = 1;
     return;