Fix x86/x86_64 getcontext overflow problem.

The x86 getcontext code was writing past the end of the context structure.
Fixed this problem, and added a test to make sure that doesn't happen again.
In addition, the x86_64 getcontext was doing the same.

Bug: 14319200
Change-Id: Ia2e2e55fe5459d6c8f8257e787012546b77503c4
diff --git a/Android.build.mk b/Android.build.mk
index e5ee80a..1a77ee8 100644
--- a/Android.build.mk
+++ b/Android.build.mk
@@ -18,6 +18,11 @@
 
 LOCAL_MODULE := $(module)
 LOCAL_MODULE_TAGS := $(module_tag)
+LOCAL_MULTILIB := $($(module)_multilib)
+ifeq ($(LOCAL_MULTILIB),both)
+    LOCAL_MODULE_STEM_32 := $(module)32
+    LOCAL_MODULE_STEM_64 := $(module)64
+endif
 
 LOCAL_ADDITIONAL_DEPENDENCIES := \
     $(LOCAL_PATH)/Android.mk \