[android] Set platform to 16 for 32 bit builds.

TBR=ulan, jochen
NOTRY=true

Review URL: https://codereview.chromium.org/1209453003

Cr-Commit-Position: refs/heads/master@{#29252}

Makefile.android

@@ -38,25 +38,25 @@ ANDROID_BUILDS = $(foreach mode,$(MODES), \
 HOST_OS = $(shell uname -s | sed -e 's/Linux/linux/;s/Darwin/mac/')
 
 ifeq ($(ARCH), android_arm)
-  DEFINES  = target_arch=arm v8_target_arch=arm android_target_arch=arm
+  DEFINES  = target_arch=arm v8_target_arch=arm android_target_arch=arm android_target_platform=16
   DEFINES += arm_neon=0 arm_version=7
 else ifeq ($(ARCH), android_arm64)
-  DEFINES  = target_arch=arm64 v8_target_arch=arm64 android_target_arch=arm64
+  DEFINES  = target_arch=arm64 v8_target_arch=arm64 android_target_arch=arm64 android_target_platform=21
 else ifeq ($(ARCH), android_mipsel)
-  DEFINES  = target_arch=mipsel v8_target_arch=mipsel
+  DEFINES  = target_arch=mipsel v8_target_arch=mipsel android_target_platform=16
   DEFINES += android_target_arch=mips mips_arch_variant=mips32r2
 else ifeq ($(ARCH), android_ia32)
-  DEFINES = target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86
+  DEFINES = target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86 android_target_platform=16
 else ifeq ($(ARCH), android_x64)
-  DEFINES = target_arch=x64 v8_target_arch=x64 android_target_arch=x86_64
+  DEFINES = target_arch=x64 v8_target_arch=x64 android_target_arch=x86_64 android_target_platform=21
 else ifeq ($(ARCH), android_x87)
-  DEFINES = target_arch=x87 v8_target_arch=x87 android_target_arch=x86
+  DEFINES = target_arch=x87 v8_target_arch=x87 android_target_arch=x86 android_target_platform=16
 else
   $(error Target architecture "${ARCH}" is not supported)
 endif
 
 # Common flags.
-DEFINES += host_os=${HOST_OS} OS=android android_target_platform=21
+DEFINES += host_os=${HOST_OS} OS=android
 
 .SECONDEXPANSION:
 $(ANDROID_BUILDS): $(OUTDIR)/Makefile.$$@