Enable multilib odex only if TARGET_2ND_ARCH is defined.

Bug: 17507247
Bug: 14694978
Change-Id: I160a37bc0970315054606829aa112b67eaee7d49
diff --git a/core/dex_preopt_odex_install.mk b/core/dex_preopt_odex_install.mk
index c3d47f7..28282ec 100644
--- a/core/dex_preopt_odex_install.mk
+++ b/core/dex_preopt_odex_install.mk
@@ -82,14 +82,16 @@
 # The preferred arch
 my_2nd_arch_prefix := $(LOCAL_2ND_ARCH_VAR_PREFIX)
 include $(BUILD_SYSTEM)/setup_one_odex.mk
+ifdef TARGET_2ND_ARCH
 ifeq ($(LOCAL_MULTILIB),both)
 # The non-preferred arch
 my_2nd_arch_prefix := $(if $(LOCAL_2ND_ARCH_VAR_PREFIX),,$(TARGET_2ND_ARCH_VAR_PREFIX))
 include $(BUILD_SYSTEM)/setup_one_odex.mk
 endif  # LOCAL_MULTILIB is both
+endif  # TARGET_2ND_ARCH
 endif  # LOCAL_MODULE_CLASS
-endif # libart
-endif # boot jar
+endif  # libart
+endif  # boot jar
 
 ifdef built_odex
 # Use pattern rule - we may have multiple installed odex files.