third_party/mesa: turn off ubsan_vptr, since it's compiled without rtti.

third_party/mesa/BUILD.gn

Index: third_party/mesa/BUILD.gn
diff --git a/third_party/mesa/BUILD.gn b/third_party/mesa/BUILD.gn
index 427d4b62c42471cb9a820ef717f77e2c886034bd..6d736e2c9cc58f71d327082b7e5c04f90941a4e9 100644
--- a/third_party/mesa/BUILD.gn
+++ b/third_party/mesa/BUILD.gn
@@ -273,6 +273,12 @@ static_library("mesa_libglslcommon") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  if (is_ubsan_vptr) {
+    # UBsan's vptr is not compatible with -fno-rtti,
+    # which is used by gallium/auxiliary/Makefile.
+    configs -= [ "//build/config/sanitizers:ubsan_vptr_flags" ]
+  }
+
   deps = [
     ":mesa_headers",
   ]
@@ -656,6 +662,12 @@ static_library("mesa") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  if (is_ubsan_vptr) {
+    # UBsan's vptr is not compatible with -fno-rtti,
+    # which is used by gallium/auxiliary/Makefile.
+    configs -= [ "//build/config/sanitizers:ubsan_vptr_flags" ]
+  }
+
   cflags = []
 
   if (is_android && !is_clang) {
@@ -710,6 +722,12 @@ loadable_module("osmesa") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  if (is_ubsan_vptr) {
+    # UBsan's vptr is not compatible with -fno-rtti,
+    # which is used by gallium/auxiliary/Makefile.
+    configs -= [ "//build/config/sanitizers:ubsan_vptr_flags" ]
+  }
+
   if (is_win) {
     sources += [ "src/src/mesa/drivers/osmesa/osmesa.def" ]