Adding libdbus-glib-1-2 install to fix Firefox installation issue

Installing libdbus-glib-1-2 facilitates a smooth and functional
Firefox experience on Linux systems. With this change robot
GUI test cases would again start working fine.

Change-Id: I808a54d75e3b6b92f284920ba2cf5fad648dee22
Signed-off-by: Rahul Maheshwari <rahulmaheshwari@in.ibm.com>
diff --git a/scripts/build-qemu-robot-docker.sh b/scripts/build-qemu-robot-docker.sh
index eccb9fa..c7d3a45 100755
--- a/scripts/build-qemu-robot-docker.sh
+++ b/scripts/build-qemu-robot-docker.sh
@@ -86,6 +86,7 @@
     expect \
     curl \
     build-essential \
+    libdbus-glib-1-2 \
     libpixman-1-0 \
     libglib2.0-0 \
     sshpass \