[android] Completly move path logic to gyp config.

Makefile.android

Index: Makefile.android
diff --git a/Makefile.android b/Makefile.android
index 67d8b8d55be116aea80be89daaa99d3d07e1d5f1..43727691d7a2be2e92b8e6fb06e3e4880e252127 100644
--- a/Makefile.android
+++ b/Makefile.android
@@ -36,68 +36,31 @@ ANDROID_BUILDS = $(foreach mode,$(MODES), \
                    $(addsuffix .$(mode),$(ANDROID_ARCHES)))
 
 HOST_OS = $(shell uname -s | sed -e 's/Linux/linux/;s/Darwin/mac/')
-ANDROID_NDK_HOST_ARCH ?= $(shell uname -m | sed -e 's/i[3456]86/x86/')
-ifeq ($(HOST_OS), linux)
-  TOOLCHAIN_DIR = linux-$(ANDROID_NDK_HOST_ARCH)
-else ifeq ($(HOST_OS), mac)
-  TOOLCHAIN_DIR = darwin-$(ANDROID_NDK_HOST_ARCH)
-else
-  $(error Host platform "${HOST_OS}" is not supported)
-endif
 
 ifeq ($(ARCH), android_arm)
-  DEFINES  = OS=android target_arch=arm v8_target_arch=arm android_target_arch=arm android_target_platform=21
+  DEFINES  = target_arch=arm v8_target_arch=arm android_target_arch=arm
   DEFINES += arm_neon=0 arm_version=7
-  TOOLCHAIN_ARCH = arm-linux-androideabi
-  TOOLCHAIN_PREFIX = $(TOOLCHAIN_ARCH)
 else ifeq ($(ARCH), android_arm64)
-  DEFINES  = OS=android target_arch=arm64 v8_target_arch=arm64 android_target_arch=arm64 android_target_platform=21
-  TOOLCHAIN_ARCH = aarch64-linux-android
-  TOOLCHAIN_PREFIX = $(TOOLCHAIN_ARCH)
+  DEFINES  = target_arch=arm64 v8_target_arch=arm64 android_target_arch=arm64
 else ifeq ($(ARCH), android_mipsel)
-  DEFINES  = OS=android target_arch=mipsel v8_target_arch=mipsel android_target_platform=21
+  DEFINES  = target_arch=mipsel v8_target_arch=mipsel
   DEFINES += android_target_arch=mips mips_arch_variant=mips32r2
-  TOOLCHAIN_ARCH = mipsel-linux-android
-  TOOLCHAIN_PREFIX = $(TOOLCHAIN_ARCH)
 else ifeq ($(ARCH), android_ia32)
-  DEFINES = OS=android target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86 android_target_platform=21
-  TOOLCHAIN_ARCH = x86
-  TOOLCHAIN_PREFIX = i686-linux-android
+  DEFINES = target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86
 else ifeq ($(ARCH), android_x64)
-  DEFINES = OS=android target_arch=x64 v8_target_arch=x64 android_target_arch=x86_64 android_target_platform=21
-  TOOLCHAIN_ARCH = x86_64
-  TOOLCHAIN_PREFIX = x86_64-linux-android
+  DEFINES = target_arch=x64 v8_target_arch=x64 android_target_arch=x86_64
 else ifeq ($(ARCH), android_x87)
-  DEFINES = OS=android target_arch=x87 v8_target_arch=x87 android_target_arch=x86 android_target_platform=21
-  TOOLCHAIN_ARCH = x86
-  TOOLCHAIN_PREFIX = i686-linux-android
+  DEFINES = target_arch=x87 v8_target_arch=x87 android_target_arch=x86
 else
   $(error Target architecture "${ARCH}" is not supported)
 endif
 
-TOOLCHAIN_PATH = \
-    ${ANDROID_NDK_ROOT}/toolchains/${TOOLCHAIN_ARCH}-4.9/prebuilt
-ANDROID_TOOLCHAIN ?= ${TOOLCHAIN_PATH}/${TOOLCHAIN_DIR}
-
-ifeq ($(wildcard $(ANDROID_TOOLCHAIN)),)
-  $(error Cannot find Android toolchain in "${ANDROID_TOOLCHAIN}".  Please \
-          check that ANDROID_NDK_ROOT and ANDROID_NDK_HOST_ARCH are set    \
-          correctly)
-endif
-
-# For mksnapshot host generation.
-DEFINES += host_os=${HOST_OS}
-DEFINES += OS=android
+# Common flags.
+DEFINES += host_os=${HOST_OS} OS=android android_target_platform=21
 
 .SECONDEXPANSION:
 $(ANDROID_BUILDS): $(OUTDIR)/Makefile.$$@
 	@$(MAKE) -C "$(OUTDIR)" -f Makefile.$@ \
-	          CXX="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-g++" \
-	          AR="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-ar" \
-	          RANLIB="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-ranlib" \
-	          CC="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-gcc" \
-	          LD="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-ld" \
-	          LINK="$(ANDROID_TOOLCHAIN)/bin/${TOOLCHAIN_PREFIX}-g++" \
 	          BUILDTYPE=$(shell echo $(subst .,,$(suffix $@)) | \
 	                      python -c "print raw_input().capitalize()") \
 	          builddir="$(shell pwd)/$(OUTDIR)/$@"
@@ -107,8 +70,6 @@ ANDROID_MAKEFILES = $(addprefix $(OUTDIR)/Makefile.,$(ANDROID_BUILDS))
 $(ANDROID_MAKEFILES):
 	GYP_GENERATORS=make-android \
 	GYP_DEFINES="${DEFINES}" \
-	CC="${ANDROID_TOOLCHAIN}/bin/${TOOLCHAIN_PREFIX}-gcc" \
-	CXX="${ANDROID_TOOLCHAIN}/bin/${TOOLCHAIN_PREFIX}-g++" \
 	PYTHONPATH="$(shell pwd)/tools/generate_shim_headers:$(shell pwd)/build:$(PYTHONPATH)" \
 	build/gyp/gyp --generator-output="${OUTDIR}" build/all.gyp \
 	              -Ibuild/standalone.gypi --depth=. \