Add ifdef LLDB_DISABLE_PYTHON around newly added use of
AddCXXSummary in FormatManager::LoadSystemFormatters(); 
that function pulls in code that assumes python; can't
be used without the ifdef.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@172300 91177308-0d34-0410-b5e6-96231b3b80d8