Switch to 32-bit-by-default host multilib build.

Also we don't need to force LLVM built from source, for we already force
LLVM to be built as 32-bit.

Bug: 13751317
Change-Id: Ifadf1988d28b60cb06316de50f5bdc1834f1acc0
diff --git a/core/Makefile b/core/Makefile
index bd2f9a0..46b23f8 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1473,7 +1473,7 @@
   INTERNAL_SDK_HOST_OS_NAME := $(HOST_OS)
 endif
 ifneq ($(HOST_OS),windows)
-  INTERNAL_SDK_HOST_OS_NAME := $(INTERNAL_SDK_HOST_OS_NAME)-$(HOST_ARCH)
+  INTERNAL_SDK_HOST_OS_NAME := $(INTERNAL_SDK_HOST_OS_NAME)-$(SDK_HOST_ARCH)
 endif
 sdk_name := $(sdk_name)_$(INTERNAL_SDK_HOST_OS_NAME)
 
@@ -1500,7 +1500,7 @@
 sdk_atree_files := \
 	$(atree_dir)/sdk.exclude.atree \
 	$(atree_dir)/sdk.atree \
-	$(atree_dir)/sdk-$(HOST_OS)-$(HOST_ARCH).atree
+	$(atree_dir)/sdk-$(HOST_OS)-$(SDK_HOST_ARCH).atree
 
 # development/build/sdk-android-<abi>.atree is used to differentiate
 # between architecture models (e.g. ARMv5TE versus ARMv7) when copying