Add support for TARGET_GLOBAL_UNSUPPORTED_CFLAGS

To ease the transition between toolchains, allow a target to specify
a list of cflags that the toolchain does not support.  These will be
filtered out of the cflags provided by the module.

Add TARGET_GLOBAL_UNSUPPORTED_CFLAGS := -fstack-protector for the
aarch64 toolchain, it does not yet suport -fstack-protector.

Change-Id: I168d0c6f131326fad305ec86fad46e6a3e03295a

core/binary.mk

@@ -97,6 +97,7 @@ my_cxx := $(LOCAL_CXX)
 my_c_includes := $(LOCAL_C_INCLUDES) $(LOCAL_C_INCLUDES_$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
 my_generated_sources := $(LOCAL_GENERATED_SOURCES)
 
+my_cflags := $(filter-out $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_GLOBAL_UNSUPPORTED_CFLAGS),$(my_cflags))
 
 # The real dependency will be added after all Android.mks are loaded and the install paths
 # of the shared libraries are determined.

core/combo/TARGET_linux-arm64.mk

@@ -91,6 +91,9 @@ TARGET_GLOBAL_CFLAGS += \
 			-include $(android_config_h) \
 			-I $(dir $(android_config_h))
 
+# HACK: globally disable -fstack-protector until the toolchain supports it
+TARGET_GLOBAL_UNSUPPORTED_CFLAGS := -fstack-protector
+
 # TODO - remove __ANDROID__ after the next aarch64 toolchain refresh
 TARGET_GLOBAL_CFLAGS += -D__ANDROID__=1