Add runtime_support_common.

Addressed the issue that we shouldn't maintain 2 copies of almost the
same code.

Change-Id: I212656f65e6c47e1167a193c1024100ae97f0028
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 74eee0b..e84df3e 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -206,6 +206,7 @@
 	src/reflection.cc \
 	src/runtime.cc \
 	src/runtime_support.cc \
+	src/runtime_support_common.cc \
 	src/signal_catcher.cc \
 	src/space.cc \
 	src/stack.cc \