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.h b/compiler/driver/compiler_options.h
index cdd9d4d..cee989b 100644
--- a/compiler/driver/compiler_options.h
+++ b/compiler/driver/compiler_options.h
@@ -270,6 +270,10 @@
     return dump_timings_;
   }
 
+  bool GetDumpPassTimings() const {
+    return dump_pass_timings_;
+  }
+
   bool GetDumpStats() const {
     return dump_stats_;
   }
@@ -316,6 +320,7 @@
   bool implicit_suspend_checks_;
   bool compile_pic_;
   bool dump_timings_;
+  bool dump_pass_timings_;
   bool dump_stats_;
 
   // Vector of methods to have verbose output enabled for.