MIPS[64]: Add support for big endian build using GN

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index c1352e3e4df4610666bbc07387e3d6c2e7e72a1e..ab593c68c7391504be68d944a41331bdb91196f3 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -327,8 +327,7 @@ config("toolchain") {
     defines += [ "_MIPS_TARGET_SIMULATOR" ]
   }
 
-  # TODO(jochen): Add support for mips.
-  if (v8_current_cpu == "mipsel") {
+  if (v8_current_cpu == "mipsel" || v8_current_cpu == "mips") {
     defines += [ "V8_TARGET_ARCH_MIPS" ]
     if (v8_can_use_fpu_instructions) {
       defines += [ "CAN_USE_FPU_INSTRUCTIONS" ]
@@ -362,15 +361,17 @@ config("toolchain") {
     # TODO(jochen): Add support for mips_arch_variant rx and loongson.
   }
 
-  # TODO(jochen): Add support for mips64.
-  if (v8_current_cpu == "mips64el") {
+  if (v8_current_cpu == "mips64el" || v8_current_cpu == "mips64") {
     defines += [ "V8_TARGET_ARCH_MIPS64" ]
     if (v8_can_use_fpu_instructions) {
       defines += [ "CAN_USE_FPU_INSTRUCTIONS" ]
     }
 
-    # TODO(jochen): Add support for big endian host byteorder.
-    defines += [ "V8_TARGET_ARCH_MIPS64_LE" ]
+    if (host_byteorder == "little") {
+      defines += [ "V8_TARGET_ARCH_MIPS64_LE" ]
+    } else if (host_byteorder == "big") {
+      defines += [ "V8_TARGET_ARCH_MIPS64_BE" ]
+    }
     if (v8_use_mips_abi_hardfloat) {
       defines += [
         "__mips_hard_float=1",