Remove libc++ from prepackaged shared libs in cts.

Commit 28acbeab18f6083299c07f9ebe769d22e49f8107 removed the dependency of
sepolicy-analyze on libc++, eliminating the only consumer of the library for the
cts host-side tests.  Remove the library since it is no longer needed but leave
the ability to add other shared libs in the future.

(cherry-pick of commit: 214a1714)

Bug: 19566396
Change-Id: I36f45c3e92c2d6370e98baa4c527835af66691fa