Use direct class pointers at allocation sites in the compiled code.

- Rather than looking up a class from its type ID (and checking if
  it's resolved/initialized, resolving/initializing if not), use
  direct class pointers, if possible (boot-code-to-boot-class pointers
  and app-code-to-boot-class pointers.)
- This results in a 1-2% speedup in Ritz MemAllocTest on Nexus 4.
- Embedding the object size (along with class pointers) caused a 1-2%
  slowdown in MemAllocTest and isn't implemented in this change.
- TODO: do the same for array allocations.
- TODO: when/if an application gets its own image, implement
  app-code-to-app-class pointers.
- Fix a -XX:gc bug.
  cf. https://android-review.googlesource.com/79460/
- Add /tmp/android-data/dalvik-cache to the list of locations to
  remove oat files in clean-oat-host.
  cf. https://android-review.googlesource.com/79550
- Add back a dropped UNLIKELY in FindMethodFromCode().
  cf. https://android-review.googlesource.com/74205

Bug: 9986565
Change-Id: I590b96bd21f7a7472f88e36752e675547559a5b1
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 90bfc9b..2591224 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -594,7 +594,7 @@
       for (const std::string& gc_option : gc_options) {
         gc::CollectorType collector_type = ParseCollectorType(gc_option);
         if (collector_type != gc::kCollectorTypeNone) {
-          parsed->collector_type_ = gc::kCollectorTypeGSS;
+          parsed->collector_type_ = collector_type;
         } else if (gc_option == "preverify") {
           parsed->verify_pre_gc_heap_ = true;
         }  else if (gc_option == "nopreverify") {