Remove libgtk-3-0:i386 from install-build-deps.sh

The CL removes libgtk-3-0:i386 from install-build-deps.sh as it fails to be
installed on the freshly installed Google glinux machine.

For more info and the errors installing the package, see
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/ODZ88EuoxK4

Change-Id: I4cf64ef3b98fd2a8a5299d4859da63c7a0c5f4f9
Reviewed-on: https://chromium-review.googlesource.com/c/1332207Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607986}

build/install-build-deps.sh

@@ -388,7 +388,6 @@ nacl_list="\
   libfontconfig1:i386
   libglib2.0-0:i386
   libgpm2:i386
-  libgtk-3-0:i386
   libncurses5:i386
   lib32ncurses5-dev
   libnss3:i386