[CMake] Make LLDBWrapPython.cpp depend on the .swig files.

Previously it would only regenerate LLDBWrapPython.cpp if one of
the .i files changed, or if lldb.swig changed.  This patch also
makes it depend on the rest of the *.swig files, so that if any
of them changes it regenerates the CMake.

llvm-svn: 232175