Fix building of static libs on universal-darwin

The static libs should not be built from sources during the top level
of a universal build. This regression was introduced in commit
495b241fa6b03345baf2b2f39aa8c06c735fccc2, which made the static
libs selectable under CONFIG_STATIC.

Change-Id: I585167e17459877e0fa7fa19e1046c3703d91c97
1 file changed