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..01e4ad427236040984b150e870cab850d00fe462 100644
--- a/third_party/mesa/BUILD.gn
+++ b/third_party/mesa/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
+import("//build/config/sanitizers/sanitizers.gni")
 
 config("mesa_headers_config") {
   include_dirs = [ "src/include" ]
@@ -273,6 +274,12 @@ static_library("mesa_libglslcommon") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  # UBsan's vptr is not compatible with -fno-rtti,
+  # which is used by gallium/auxiliary/Makefile.
+  configs -= [ "//build/config/sanitizers:default_sanitizer_flags" ]
+  configs +=
+      [ "//build/config/sanitizers:default_sanitizer_flags_but_ubsan_vptr" ]
+
   deps = [
     ":mesa_headers",
   ]
@@ -656,6 +663,12 @@ static_library("mesa") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  # UBsan's vptr is not compatible with -fno-rtti,
+  # which is used by gallium/auxiliary/Makefile.
+  configs -= [ "//build/config/sanitizers:default_sanitizer_flags" ]
+  configs +=
+      [ "//build/config/sanitizers:default_sanitizer_flags_but_ubsan_vptr" ]
+
   cflags = []
 
   if (is_android && !is_clang) {
@@ -710,6 +723,12 @@ loadable_module("osmesa") {
     configs -= [ "//build/config/clang:extra_warnings" ]
   }
 
+  # UBsan's vptr is not compatible with -fno-rtti,
+  # which is used by gallium/auxiliary/Makefile.
+  configs -= [ "//build/config/sanitizers:default_sanitizer_flags" ]
+  configs +=
+      [ "//build/config/sanitizers:default_sanitizer_flags_but_ubsan_vptr" ]
+
   if (is_win) {
     sources += [ "src/src/mesa/drivers/osmesa/osmesa.def" ]