Switch to using clang-3289846.

Bug: http://b/30252254
Test: Built/boot platform using latest prebuilts.
Change-Id: I47c5e8255f84b6f41d1d3e1f3c986e8699ac573a
diff --git a/cc/config/global.go b/cc/config/global.go
index d17a7d1..0a7bdc5 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -124,7 +124,7 @@
 		if override := config.(android.Config).Getenv("LLVM_PREBUILTS_VERSION"); override != "" {
 			return override, nil
 		}
-		return "clang-3217047", nil
+		return "clang-3289846", nil
 	})
 	pctx.StaticVariable("ClangPath", "${ClangBase}/${HostPrebuiltTag}/${ClangVersion}")
 	pctx.StaticVariable("ClangBin", "${ClangPath}/bin")