Allow x86+arm multilib build.

The explicit dependency of dex2oat on installed file of libart-compiler
isn't necessary: the build sets up the dependency automatically when
dex2oat links liblibart-compiler.
Also the way of the explicit dependency is incorrect if multilib is
involved: a 64-bit dex2oat may depend on 32-bit libart-compiler.

Bug: 27526885
Change-Id: I4a9d72b49f5712695ff5a32b88df5eab9df7c1e4
(cherry-pick from commit 5eec66ea27a2fa5bfa1b4f9bd203c76e2990d7a2)
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 6952d69..6befec5 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -63,7 +63,11 @@
     ART_TARGET_ARCH_64 := $(TARGET_ARCH)
   else
     # TODO: ???
-    $(error Do not know what to do with this multi-target configuration!)
+    $(warning Do not know what to do with this multi-target configuration!)
+    ART_PHONY_TEST_TARGET_SUFFIX := 32
+    2ND_ART_PHONY_TEST_TARGET_SUFFIX :=
+    ART_TARGET_ARCH_32 := $(TARGET_ARCH)
+    ART_TARGET_ARCH_64 :=
   endif
 else
   ifneq ($(filter %64,$(TARGET_ARCH)),)