Split WITHOUT_CLANG to WITHOUT_HOST_CLANG and WITHOUT_TARGET_CLANG

Still keep WITHOUT_CLANG, which enables both.

Bug: 13402154
Change-Id: I32cb668223997719875751bf3d64f592d6086830
diff --git a/core/clang/config.mk b/core/clang/config.mk
index 1fd69d7..96f860d 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -1,3 +1,11 @@
+## Clang configurations.
+
+# WITHOUT_CLANG covers both HOST and TARGET
+ifeq ($(WITHOUT_CLANG),true)
+WITHOUT_TARGET_CLANG := true
+WITHOUT_HOST_CLANG := true
+endif
+
 ifeq (true,$(FORCE_BUILD_LLVM_COMPONENTS))
 LLVM_PREBUILTS_PATH := $(BUILD_OUT_EXECUTABLES)
 LLVM_PREBUILTS_HEADER_PATH := external/clang/lib/include