Switch to clang-3859424.

Bug: http://b/36442361
Test: Build and run multiple devices/targets.
Change-Id: Ib2ba71acdc5ae5100122bb498c5a51db74953d42
diff --git a/cc/config/global.go b/cc/config/global.go
index 1ce1cce..50c7c98 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -132,7 +132,7 @@
 		if override := config.(android.Config).Getenv("LLVM_PREBUILTS_VERSION"); override != "" {
 			return override, nil
 		}
-		return "clang-3688880", nil
+		return "clang-3859424", nil
 	})
 	pctx.StaticVariable("ClangPath", "${ClangBase}/${HostPrebuiltTag}/${ClangVersion}")
 	pctx.StaticVariable("ClangBin", "${ClangPath}/bin")