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.

Bug: 19566396
Change-Id: I4fbfa44ce9f099ad058fd0630ac48749e389e3e1