[NaCl SDK] Cleanup references to old newlib toolchain

native_client_sdk/src/gonacl_appengine/src/earth/Makefile

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GNU Makefile based on shared rules provided by the Native Client SDK.
 # See README.Makefiles for more details.
 
-VALID_TOOLCHAINS := newlib glibc pnacl
+VALID_TOOLCHAINS := clang-newlib glibc pnacl
 
 NACL_SDK_ROOT ?= $(abspath $(CURDIR)/../../..)
 include $(NACL_SDK_ROOT)/tools/common.mk
 
 TARGET = earth
 LIBS = $(DEPS) ppapi_simple nacl_io sdk_util ppapi_cpp ppapi pthread
 
 CFLAGS = -Wall -I..
 SOURCES = earth.cc
 
 # Build rules generated by macros from common.mk:
 
 $(foreach src,$(SOURCES),$(eval $(call COMPILE_RULE,$(src),$(CFLAGS))))
 
 # The PNaCl workflow uses both an unstripped and finalized/stripped binary.
 # On NaCl, only produce a stripped binary for Release configs (not Debug).
 ifneq (,$(or $(findstring pnacl,$(TOOLCHAIN)),$(findstring Release,$(CONFIG))))
 $(eval $(call LINK_RULE,$(TARGET)_unstripped,$(SOURCES),$(LIBS),$(DEPS)))
 $(eval $(call STRIP_RULE,$(TARGET),$(TARGET)_unstripped))
 else
 $(eval $(call LINK_RULE,$(TARGET),$(SOURCES),$(LIBS),$(DEPS)))
 endif
 
 $(eval $(call NMF_RULE,$(TARGET),))