Switch ART to libc++.

TODO: remove all vestiges of stlport.

Change-Id: I95a3cb0b53d0898f0a5d388b606e79522f4d85e0
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 5341136..175cc6e 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -247,7 +247,7 @@
 ART_TARGET_CFLAGS += $(ART_DEFAULT_GC_TYPE_CFLAGS)
 
 # TODO: remove when target no longer implies stlport.
-ART_TARGET_CFLAGS += -DART_WITH_STLPORT=1
+# ART_TARGET_CFLAGS += -DART_WITH_STLPORT=1
 
 # DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES is set in ../build/core/dex_preopt.mk based on
 # the TARGET_CPU_VARIANT