Preparation for transition to libc++.

Move the dependency on libc++ to its own makefile so that we can switch in a
single place between libc++ and stlport.

Change-Id: Ie61e7d054dcd049e36d5e7298c27d8a4abe6edf7
diff --git a/build/Android.gtest.mk b/build/Android.gtest.mk
index 24acc56..b6e6fac 100644
--- a/build/Android.gtest.mk
+++ b/build/Android.gtest.mk
@@ -150,10 +150,6 @@
   art_gtest_name := $$(notdir $$(basename $$(art_gtest_filename)))
 
   include $(CLEAR_VARS)
-  ifeq ($$(art_target_or_host),target)
-    include external/stlport/libstlport.mk
-  endif
-
   LOCAL_CPP_EXTENSION := $(ART_CPP_EXTENSION)
   LOCAL_MODULE := $$(art_gtest_name)
   ifeq ($$(art_target_or_host),target)
@@ -184,6 +180,7 @@
     LOCAL_MODULE_PATH_32 := $(ART_BASE_NATIVETEST_OUT)
     LOCAL_MODULE_PATH_64 := $(ART_BASE_NATIVETEST_OUT)64
     LOCAL_MULTILIB := both
+    include art/build/Android.libcxx.mk
     include $(BUILD_EXECUTABLE)
     ART_TARGET_GTEST_EXECUTABLES += $$(art_gtest_exe)
     art_gtest_target := test-art-$$(art_target_or_host)-gtest-$$(art_gtest_name)
@@ -208,6 +205,8 @@
         LOCAL_STATIC_LIBRARIES += libgtest_host
     endif
     LOCAL_LDLIBS += -lpthread -ldl
+    LOCAL_IS_HOST_MODULE := true
+    include art/build/Android.libcxx.mk
     include $(BUILD_HOST_EXECUTABLE)
     art_gtest_exe := $(HOST_OUT_EXECUTABLES)/$$(LOCAL_MODULE)
     ART_HOST_GTEST_EXECUTABLES += $$(art_gtest_exe)