[TestLoadUnload] Enable for Android while skipping it for other remotes.

Summary:
This change adds all the necessary infrastructure required to
selectively enable and make TestLoadUnload work for Android. One test,
which tests the module search paths, is still kept disabled for remote
as search paths (because of module caching) are local anyway.

Reviewers: tberghammer

Reviewed By: tberghammer

Subscribers: emaste, lldb-commits, tberghammer

Differential Revision: http://reviews.llvm.org/D10469

llvm-svn: 239965