Add HOST_PREFER_32_BIT to support 32-bit-by-default multilib build

We already support pure 32-bit and 64-bit-by-default multilib build.
With HOST_PREFER_32_BIT we can build 32-bit-by-default multilib build.
This will be lest disruptive during the period we transition to
64-bit-by-default.

Bug: 13751317
Change-Id: I0d56ce4abbe4afeaacfd70d709f6a349791c0722
diff --git a/core/host_executable.mk b/core/host_executable.mk
index 874bf87..53b5fd1 100644
--- a/core/host_executable.mk
+++ b/core/host_executable.mk
@@ -3,9 +3,13 @@
 include $(BUILD_SYSTEM)/multilib.mk
 
 ifndef my_module_multilib
+ifeq ($(HOST_PREFER_32_BIT),true)
+my_module_multilib := 32
+else
 # By default we only build host module for the first arch.
 my_module_multilib := first
 endif
+endif
 
 ifeq ($(my_module_multilib),both)
 ifeq ($(LOCAL_MODULE_PATH_32)$(LOCAL_MODULE_STEM_32),)
@@ -33,9 +37,6 @@
 OVERRIDE_BUILT_MODULE_PATH :=
 LOCAL_BUILT_MODULE :=
 LOCAL_INSTALLED_MODULE :=
-LOCAL_MODULE_STEM :=
-LOCAL_BUILT_MODULE_STEM :=
-LOCAL_INSTALLED_MODULE_STEM :=
 LOCAL_INTERMEDIATE_TARGETS :=
 
 include $(BUILD_SYSTEM)/host_executable_internal.mk