ART: Add --dump-pass-timings compiler option.

This replaces the old --dump-passes option removed in
    https://android-review.googlesource.com/549200 .
Using --dump-timing for timing optimization passes makes
the high level timings useless, so return to using two
different options for these.

Test: Manually run dex2oat with --dump-timings,
      --dump-pass-timings and both.
Change-Id: Iddc4cfee35652fb493656e7d6081a898c2894f72
diff --git a/compiler/driver/compiler_options.cc b/compiler/driver/compiler_options.cc
index 2d82d79..933be4f 100644
--- a/compiler/driver/compiler_options.cc
+++ b/compiler/driver/compiler_options.cc
@@ -51,6 +51,7 @@
       implicit_suspend_checks_(false),
       compile_pic_(false),
       dump_timings_(false),
+      dump_pass_timings_(false),
       dump_stats_(false),
       verbose_methods_(),
       abort_on_hard_verifier_failure_(false),