Disable clang for mips/mips64 libc.

* Many processes, including adbd, failed to start in mips/mips64
  emulator when libc.so was compiled by clang.

BUG: 25291096
Change-Id: If3434ebdca4a3a6bf6102b120ee838a7ab66cd74
diff --git a/libc/Android.mk b/libc/Android.mk
index a89fe23..601a3d7 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -623,6 +623,11 @@
   use_clang := false
 endif
 
+# b/25291096, Clang/llvm compiled libc.so for mips/mips64 failed to boot.
+ifeq ($(TARGET_ARCH),$(filter $(TARGET_ARCH),mips mips64))
+  use_clang := false
+endif
+
 ifeq ($(use_clang),)
   use_clang := false
 endif