[libfuzzer] Add 'vptr' flag to builds with UndefinedBehaviourSanitizer.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 1080 matching lines @@
 
 config("rtti") {
   if (is_win) {
     cflags_cc = [ "/GR" ]
   } else {
     cflags_cc = [ "-frtti" ]
   }
 }
 config("no_rtti") {
   # CFI diagnostics and UBsan vptr require RTTI.
-  if (!use_cfi_diag && !is_ubsan_vptr) {
+  if (!use_cfi_diag && !is_ubsan_vptr && !is_ubsan_security) {
     if (is_win) {
       cflags_cc = [ "/GR-" ]
     } else {
       cflags_cc = [ "-fno-rtti" ]
       cflags_objcc = cflags_cc
     }
   }
 }
 
 # Warnings ---------------------------------------------------------------------
@@ skipping 351 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }