Refactor the code.

The object hierarchy was confusing and convoluted. This removes
a lot of unnecessary code, and consolidates the BacktraceCurrent
and BacktraceThread code into BacktraceCurrent.

Change-Id: I01c8407d493712a48169df49dd3ff46db4a7c3ae
diff --git a/libbacktrace/Android.build.mk b/libbacktrace/Android.build.mk
index d7eaa68..ded0aac 100644
--- a/libbacktrace/Android.build.mk
+++ b/libbacktrace/Android.build.mk
@@ -19,28 +19,34 @@
 LOCAL_MODULE := $(module)
 LOCAL_MODULE_TAGS := $(module_tag)
 LOCAL_MULTILIB := $($(module)_multilib)
+ifeq ($(LOCAL_MULTILIB),both)
+ifneq ($(build_target),$(filter $(build_target),SHARED_LIBRARY STATIC_LIBRRARY))
+  LOCAL_MODULE_STEM_32 := $(LOCAL_MODULE)32
+  LOCAL_MODULE_STEM_64 := $(LOCAL_MODULE)64
+endif
+endif
 
 LOCAL_ADDITIONAL_DEPENDENCIES := \
     $(LOCAL_PATH)/Android.mk \
     $(LOCAL_PATH)/Android.build.mk \
 
 LOCAL_CFLAGS := \
-    $(common_cflags) \
+    $(libbacktrace_common_cflags) \
     $($(module)_cflags) \
     $($(module)_cflags_$(build_type)) \
 
 LOCAL_CONLYFLAGS += \
-    $(common_conlyflags) \
+    $(libbacktrace_common_conlyflags) \
     $($(module)_conlyflags) \
     $($(module)_conlyflags_$(build_type)) \
 
 LOCAL_CPPFLAGS += \
-    $(common_cppflags) \
+    $(libbacktrace_common_cppflags) \
     $($(module)_cppflags) \
     $($(module)_cppflags_$(build_type)) \
 
 LOCAL_C_INCLUDES := \
-    $(common_c_includes) \
+    $(libbacktrace_common_c_includes) \
     $($(module)_c_includes) \
     $($(module)_c_includes_$(build_type)) \