Switch to clang-r383902 (11.0.1).

Also suppress some warnings/flags globally to pass compilation.

Bug: 149839606
Test: build aosp_arm64-userdebug.
Change-Id: I0ed740e51b6b39c58842a58eabcf3cdf404e73fa
diff --git a/cc/config/global.go b/cc/config/global.go
index d85ac5f..d5ecf7f 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -128,8 +128,8 @@
 
 	// prebuilts/clang default settings.
 	ClangDefaultBase         = "prebuilts/clang/host"
-	ClangDefaultVersion      = "clang-r377782d"
-	ClangDefaultShortVersion = "10.0.6"
+	ClangDefaultVersion      = "clang-r383902"
+	ClangDefaultShortVersion = "11.0.1"
 
 	// Directories with warnings from Android.bp files.
 	WarningAllowedProjects = []string{