Move enablement of rhel6-optional repo earlier

Change 4f1fee6eae300a3384900df06ebc857e95854eb0 added the RHEL6
optional repo in fixup_stuff.sh, but it turns out that doesn't get run
until after the package prerequisites phase.  Move this into stack.sh
with the RDO repo setup.

Change-Id: Iae0df85fa94c6c1b6f497dd29fda90d03b903a41
diff --git a/stack.sh b/stack.sh
index 9cdf264..217afbc 100755
--- a/stack.sh
+++ b/stack.sh
@@ -194,6 +194,10 @@
         yum_install ${RHEL6_EPEL_RPM} || \
             die $LINENO "Error installing EPEL repo, cannot continue"
     fi
+
+    # ... and also optional to be enabled
+    sudo yum-config-manager --enable rhel-6-server-optional-rpms
+
 fi
 
 
diff --git a/tools/fixup_stuff.sh b/tools/fixup_stuff.sh
index 048024a..47b0cd1 100755
--- a/tools/fixup_stuff.sh
+++ b/tools/fixup_stuff.sh
@@ -98,10 +98,6 @@
         sudo setenforce 0
     fi
 
-    # make sure we have the "optional" repo enabled; it provides some
-    # packages like libffi-devel for example
-    sudo yum-config-manager --enable rhel-6-server-optional-rpms
-
     # If the ``dbus`` package was installed by DevStack dependencies the
     # uuid may not be generated because the service was never started (PR#598200),
     # causing Nova to stop later on complaining that ``/var/lib/dbus/machine-id``