Remove LOCAL_CLANG := false support

Only clang is supported now.

Test: build/soong/build_test.bash in all downstream branches
Change-Id: Ie8ad009625ddd7d5c38a6276b631bc889974fda3

core/binary.mk

@@ -339,11 +339,10 @@ ifneq ($(my_cc)$(my_cxx),)
         my_clang := false
     endif
 endif
-# Issue warning if LOCAL_CLANG* is set to false and the local makefile is not found
-# in the exception project list.
 ifeq ($(my_clang),false)
-    ifeq ($(call find_in_local_clang_exception_projects,$(LOCAL_MODULE_MAKEFILE))$(LOCAL_IS_AUX_MODULE),)
-        $(error $(LOCAL_MODULE_MAKEFILE): $(LOCAL_MODULE): LOCAL_CLANG is set to false)
+    # https://android-review.googlesource.com/720799
+    ifneq ($(LOCAL_MODULE),bionic-compile-time-tests-g++)
+        $(call pretty-error,LOCAL_CLANG false is no longer supported)
     endif
 endif
 
@@ -351,10 +350,7 @@ endif
 # enable it unless we've specifically disabled clang above
 ifdef LOCAL_IS_HOST_MODULE
     ifneq ($($(my_prefix)CLANG_SUPPORTED),true)
-        ifeq ($(my_clang),true)
-            $(call pretty-error,Clang is not yet supported for $($(my_prefix)OS) binaries)
-        endif
-        my_clang := false
+        $(error $($(my_prefix)OS) requires GCC$(comma) but only Clang is supported)
     else
         ifeq ($(my_clang),)
             my_clang := true

core/clang/config.mk

@@ -68,28 +68,4 @@ endif
 # provides to Clang (for supporting features like -ftrapv).
 COMPILER_RT_CONFIG_EXTRA_STATIC_LIBRARIES := libcompiler_rt-extras
 
-# A list of projects that are allowed to set LOCAL_CLANG to false.
-# INTERNAL_LOCAL_CLANG_EXCEPTION_PROJECTS is defined later in other config.mk.
-LOCAL_CLANG_EXCEPTION_PROJECTS = \
-  bionic/tests/ \
-  device/google/contexthub/ \
-  device/huawei/angler/ \
-  device/lge/bullhead/ \
-  external/gentoo/integration/ \
-  hardware/qcom/ \
-  test/vts/hals/camera/bullhead/ \
-  test/vts/hals/etc/libqdutils/ \
-  vendor/huawei/angler/ \
-  vendor/lge/bullhead/ \
-  $(INTERNAL_LOCAL_CLANG_EXCEPTION_PROJECTS)
-
-# Find $1 in the exception project list.
-define find_in_local_clang_exception_projects
-$(subst $(space),, \
-  $(foreach project,$(LOCAL_CLANG_EXCEPTION_PROJECTS), \
-    $(if $(filter $(project)%,$(1)),$(project)) \
-  ) \
-)
-endef
-
 include $(BUILD_SYSTEM)/clang/tidy.mk