[flags] Fix initialization order in sample shell

Flags need to be set before initializing V8.

R=cbruni@chromium.org

Bug: v8:12887
Change-Id: Idb815a6a85ccb86c79d826da487a7bbc6fab7d1a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3707096
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81178}

samples/shell.cc

@@ -79,8 +79,8 @@ int main(int argc, char* argv[]) {
     return 1;
   }
 #endif
-  v8::V8::Initialize();
   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
+  v8::V8::Initialize();
   v8::Isolate::CreateParams create_params;
   create_params.array_buffer_allocator =
       v8::ArrayBuffer::Allocator::NewDefaultAllocator();