Fix handling of v8_builtins_profiling_log_file gn argument

There were two problems:
1. v8_builtins_profiling_log_file was not declared in "sources" or
   "inputs", so Ninja wouldn't re-run mksnapshot if it changed.
2. v8_builtins_profiling_log_file was passed directly to mksnapshot
   without rebasing the path, which makes it awkward and inconsistent
   with how most other gn arguments work.

Bug: v8:10470
Change-Id: Id8edba325b867e8d9561d3c76f28e121641d0dd4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2434103Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#70199}

BUILD.gn

@@ -1536,9 +1536,10 @@ template("run_mksnapshot") {
       args += [ "--turbo-profiling-verbose" ]
     }
     if (v8_builtins_profiling_log_file != "") {
+      sources += [ v8_builtins_profiling_log_file ]
       args += [
         "--turbo-profiling-log-file",
-        v8_builtins_profiling_log_file,
+        rebase_path(v8_builtins_profiling_log_file, root_build_dir),
       ]
     }