[gn] Add gn configs for mips to match old behavior

BUILD.gn

 # Copyright 2014 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/arm.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
@@ skipping 76 matching lines @@
 }
 
 # Derived defaults.
 if (v8_object_print == "") {
   v8_object_print = is_debug && !v8_optimized_debug
 }
 if (v8_enable_disassembler == "") {
   v8_enable_disassembler = is_debug && !v8_optimized_debug
 }
 
+# Specifies if the target build is a simulator build. Comparing target cpu
+# with v8 target cpu to not affect simulator builds for making cross-compile
+# snapshots.
+is_target_simulator = target_cpu != v8_target_cpu
+
 v8_generated_peephole_source = "$target_gen_dir/bytecode-peephole-table.cc"
 v8_random_seed = "314159265"
 v8_toolset_for_shell = "host"
 
 ###############################################################################
 # Configurations
 #
 config("internal_config") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
@@ skipping 122 matching lines @@
         defines += [ "USE_EABI_HARDFLOAT=1" ]
       } else if (arm_float_abi == "softfp") {
         defines += [ "USE_EABI_HARDFLOAT=0" ]
       }
     }
   }
   if (v8_current_cpu == "arm64") {
     defines += [ "V8_TARGET_ARCH_ARM64" ]
   }
 
+  # Mips64el/mipsel simulators.
+  if (is_target_simulator &&
+      (v8_current_cpu == "mipsel" || v8_current_cpu == "mips64el")) {
+    defines += [ "_MIPS_TARGET_SIMULATOR" ]
+  }
+
   # TODO(jochen): Add support for mips.
   if (v8_current_cpu == "mipsel") {
     defines += [ "V8_TARGET_ARCH_MIPS" ]
     if (v8_can_use_fpu_instructions) {
       defines += [ "CAN_USE_FPU_INSTRUCTIONS" ]
     }
     if (v8_use_mips_abi_hardfloat) {
       defines += [
         "__mips_hard_float=1",
         "CAN_USE_FPU_INSTRUCTIONS",
@@ skipping 2360 matching lines @@
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }
 
 v8_fuzzer("wasm_code_fuzzer") {
 }