ART: remove gcc cruft from the makefiles

ART only builds with clang now, delete all logic to determine gcc
vs. clang, and move all LOCAL_CLANG_CFLAGS into LOCAL_CFLAGS.

Test: mma, make test-art-host, make test-art-target
Change-Id: I578615233ad3e71af18afb47bb11f3be8417216c
diff --git a/build/Android.executable.mk b/build/Android.executable.mk
index 157500b..2db16af 100644
--- a/build/Android.executable.mk
+++ b/build/Android.executable.mk
@@ -80,12 +80,11 @@
   endif
 
   ifeq ($$(art_target_or_host),target)
-    $(call set-target-local-clang-vars)
+    LOCAL_CLANG := $(ART_TARGET_CLANG)
     $(call set-target-local-cflags-vars,$(6))
     LOCAL_SHARED_LIBRARIES += libdl
   else # host
     LOCAL_CLANG := $(ART_HOST_CLANG)
-    LOCAL_LDLIBS := $(ART_HOST_LDLIBS)
     LOCAL_CFLAGS += $(ART_HOST_CFLAGS)
     LOCAL_ASFLAGS += $(ART_HOST_ASFLAGS)
     ifeq ($$(art_ndebug_or_debug),debug)