Do not build art with clang for mips64

Clang generates illegal instruction on mips64r6 with -O0.
https://dmz-portal.mips.com/bugz/show_bug.cgi?id=2218

BUG: 25928358

Change-Id: I8ccd644f1509b4b341384fa67facc07cb966dfa8
diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index cd9d18d..a93d8a8 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -118,7 +118,8 @@
 ART_TARGET_CLANG_arm := false
 ART_TARGET_CLANG_arm64 :=
 ART_TARGET_CLANG_mips :=
-ART_TARGET_CLANG_mips64 :=
+# b/25928358, illegal instruction on mips64r6 with -O0
+ART_TARGET_CLANG_mips64 := false
 ART_TARGET_CLANG_x86 :=
 ART_TARGET_CLANG_x86_64 :=