[gn] Switch linux64 debug and internal snapshot to gn

gni/isolate.gni

Index: gni/isolate.gni
diff --git a/gni/isolate.gni b/gni/isolate.gni
index e6d166c4603228eba59412cfe309c10d1ab38e40..c2c025ce0c19f3a020c00ee60db71c1dff007602 100644
--- a/gni/isolate.gni
+++ b/gni/isolate.gni
@@ -101,6 +101,11 @@ template("v8_isolate_run") {
       } else {
         use_snapshot = "false"
       }
+      if (v8_has_valgrind) {
+        has_valgrind = "1"
+      } else {
+        has_valgrind = "0"
+      }
 
       # Note, all paths will be rebased in isolate_driver.py to be relative to
       # the isolate file.
@@ -132,7 +137,7 @@ template("v8_isolate_run") {
         "--config-variable",
         "gcmole=0",
         "--config-variable",
-        "has_valgrind=0",
+        "has_valgrind=$has_valgrind",
         "--config-variable",
         "icu_use_data_file_flag=$icu_use_data_file_flag",
         "--config-variable",