Rewrite method matching in UnstartedRuntime.

Use the `ArtMethod*` as the key in the maps to avoid
the `PrettyMethod()` overhead.

Remove ByteOrder.isLittleEndian() implementation from
UnstartedRuntime. The Java method has been removed by
    https://android-review.googlesource.com/151062 .

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: boots.
Bug: 175869411
Change-Id: I97cf91a0abf2b28f83562d8764d28edafa1a09e2
diff --git a/runtime/common_runtime_test.cc b/runtime/common_runtime_test.cc
index 16f0d58..4509573 100644
--- a/runtime/common_runtime_test.cc
+++ b/runtime/common_runtime_test.cc
@@ -142,6 +142,8 @@
   if (!unstarted_initialized_) {
     interpreter::UnstartedRuntime::Initialize();
     unstarted_initialized_ = true;
+  } else {
+    interpreter::UnstartedRuntime::Reinitialize();
   }
 
   {