Pull in r170135 from upstream clang trunk:

Pull in r170135 from upstream clang trunk:

  Dont use/link ARCMT, StaticAnalyzer and Rewriter to clang when the user
  specifies not to. Dont build ASTMatchers with Rewriter disabled and
  StaticAnalyzer when it's disabled.

  Without all those three, the clang binary shrinks (x86_64) from ~36MB
  to ~32MB (unstripped).

To disable these clang components, and get a smaller clang binary built
and installed, set WITHOUT_CLANG_FULL in src.conf(5).  During the
initial stages of buildworld, those extra components are already
disabled automatically, to save some build time.

MFC after:	1 week