Use PARALLEL_DIRS instead of DIRS in the Makefile
based build since the subdirectories all appear to
have no inter-directory dependencies. This speeds
up parallel makefile builds greatly.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@219660 91177308-0d34-0410-b5e6-96231b3b80d8