Fix valgrind gtests and memory leaks.

All tests pass other than image_test which passes if some bad reads
are disabled (buzbee working on this).

Change-Id: Ifd6b6e3aed0bc867703b6e818353a9f296609422
diff --git a/compiler/oat_writer.cc b/compiler/oat_writer.cc
index 186ab38..5394bbc 100644
--- a/compiler/oat_writer.cc
+++ b/compiler/oat_writer.cc
@@ -1014,6 +1014,7 @@
 }
 
 OatWriter::OatClass::~OatClass() {
+  delete method_bitmap_;
   delete compiled_methods_;
 }