[CMake] Make the unittests link against everything...

Sigh.  There's really not a good alternative until we decouple
python from lldb better.  The only way the build works right now
is by having every executable link against every LLDB library.
This causes implicit transitive link dependencies on the union
of everything that LLDB brings in.  Which means that if all we
want is one header file from interpreter, we have to bring in
everything, including everything that everything depends on,
which means python.

There's outstanding efforts to address this, but it's not yet
complete.  So until then, this is all we can do.

llvm-svn: 232287