Add squiggles in c_cpp_properties.json for browse.databaseFilename if it is not the first folder in the multi-root workspace

Version info

• OS and Version: MacOS 11.1
• VS Code Version: 1.52.1
• C/C++ Extension Version: 1.2.0-insiders2
• Other extensions you installed (and if the issue persists after disabling them): Tried without every other extension

Bug description

I have set browse.databaseFilename in my c_cpp_properties.json, unfortunately it looks like that property isn't used/applied. But i already found out why it isn't working.

Content of my c_cpp_properties.json:

{
    "configurations": [
        {
            "name": "Configuration 1",
            "defines": [],
            "cStandard": "c11",
            "cppStandard": "c++17",
            "intelliSenseMode": "clang-x64",
            "browse": {
                "databaseFilename": "/tmp/vscode/browse_config10.db"
            }
        }
    ],
    "version": 4
}

Now here comes the thing: I noticed that the order of workspace folders is affecting this behavior. Here is the content of my workspace json file:

{
	"folders": [
		{
			"path": "build"
		},
		{
			"path": "src"
		},
	],
	"settings": {
		"C_Cpp.loggingLevel": "Debug",
	}
}

This is my folder/file structue:

├── build
│   └── .vscode
│       └── settings.json
├── src
│   ├── .vscode
│   │   └── c_cpp_properties.json
│   └── main.cpp
└── workspace.code-workspace

As soon as i put the src folder to the top (where c_cpp_properties.json is located in), it works as expected!

"folders": [
	{
		"path": "src"
	},
	{
		"path": "build"
	}
],

Maybe this is intended and I'm not aware of, but i don't think so.
I attached a zipfile with my minimal example, so this should be easy to reproduce: code_workspace.zip

Reproduce the issue with the attached code_workspace.zip, using the workspace JSON with build before src and then reversing the folder order. Start with src/.vscode/c_cpp_properties.json and the browse.databaseFilename handling; done means the configured database path is applied regardless of folder order and the reported invalid configuration receives the requested squiggles.