Add basic Darwin support to libcorkscrew.

This might not seem like much, but it's already better than Mac OS'
backtrace(3).

(cherry picked from commit 2a46f6293f19b9d6100187fbd53088088e671b88)

Change-Id: I197b06c4c19f728ad6f194b2f473bd9dcd99b8a6
diff --git a/libcorkscrew/Android.mk b/libcorkscrew/Android.mk
index 2786d8f..20c48c3 100644
--- a/libcorkscrew/Android.mk
+++ b/libcorkscrew/Android.mk
@@ -59,23 +59,26 @@
 
 # Build test.
 include $(CLEAR_VARS)
-LOCAL_SRC_FILES := test.c
-LOCAL_CFLAGS += -std=gnu99 -Werror -fno-inline-small-functions
+LOCAL_SRC_FILES := test.cpp
+LOCAL_CFLAGS += -Werror -fno-inline-small-functions
 LOCAL_SHARED_LIBRARIES := libcorkscrew
 LOCAL_MODULE := libcorkscrew_test
 LOCAL_MODULE_TAGS := optional
 include $(BUILD_EXECUTABLE)
 
 
-ifeq ($(HOST_OS)-$(HOST_ARCH),linux-x86)
+ifeq ($(HOST_ARCH),x86)
 
 # Build libcorkscrew.
 include $(CLEAR_VARS)
 LOCAL_SRC_FILES += $(generic_src_files) $(x86_src_files)
 LOCAL_CFLAGS += -DCORKSCREW_HAVE_ARCH
-LOCAL_SHARED_LIBRARIES += libgccdemangle
 LOCAL_STATIC_LIBRARIES += libcutils
-LOCAL_LDLIBS += -ldl -lrt
+LOCAL_LDLIBS += -ldl
+ifeq ($(HOST_OS),linux)
+  LOCAL_SHARED_LIBRARIES += libgccdemangle # TODO: is this even needed on Linux?
+  LOCAL_LDLIBS += -lrt
+endif
 LOCAL_CFLAGS += -std=gnu99 -Werror
 LOCAL_MODULE := libcorkscrew
 LOCAL_MODULE_TAGS := optional
@@ -83,11 +86,11 @@
 
 # Build test.
 include $(CLEAR_VARS)
-LOCAL_SRC_FILES := test.c
-LOCAL_CFLAGS += -std=gnu99 -Werror -fno-inline-small-functions
+LOCAL_SRC_FILES := test.cpp
+LOCAL_CFLAGS += -Werror
 LOCAL_SHARED_LIBRARIES := libcorkscrew
 LOCAL_MODULE := libcorkscrew_test
 LOCAL_MODULE_TAGS := optional
 include $(BUILD_HOST_EXECUTABLE)
 
-endif # linux-x86
+endif # HOST_ARCH == x86