Invert dependency between lldb-framework and lldb-suite

Summary:
Currently, if you build lldb-framework the entire framework doesn't
actually build. In order to build the entire framework, you need to actually
build lldb-suite. This abstraction doesn't feel quite right because
lldb-framework truly does depend on lldb-suite (liblldb + related tools).

In this change I want to invert their dependency. This will mean that lldb and
finish_swig will depend on lldb-framework in a framework build, and lldb-suite
otherwise. Instead of adding conditional logic everywhere to handle this, I
introduce LLDB_SUITE_TARGET to handle it.

Differential Revision: https://reviews.llvm.org/D49406

llvm-svn: 337311