Fix for test-art-host

Courtesy of dallison@

Change-Id: I160a5c84c176f22168bf236899349b6087494807
diff --git a/build/Android.common.mk b/build/Android.common.mk
index aa167b2..a14b951 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -37,7 +37,11 @@
 ART_BUILD_HOST_NDEBUG ?= $(WITH_HOST_DALVIK)
 ART_BUILD_HOST_DEBUG ?= $(WITH_HOST_DALVIK)
 
+ifeq ($(HOST_PREFER_32_BIT),true)
+ART_HOST_ARCH := $(HOST_2ND_ARCH)
+else
 ART_HOST_ARCH := $(HOST_ARCH)
+endif
 
 ifeq ($(ART_BUILD_TARGET_NDEBUG),false)
 $(info Disabling ART_BUILD_TARGET_NDEBUG)