RFR: 8306281: function isWsl() returns false on WSL2

[Erik Joelsson]

On Mon, 12 Jun 2023 09:46:50 GMT, Ivan Bereziuk <duke at openjdk.org> wrote:

> Currently _isWsl()_ function is looking for "Microsoft" string in the _kernel release_ string (`$ uname -r`). 
> That's not always true. Namely, on Ubuntu 22.04 - currently the newest Ubuntu LTS and default OS for WSL in Microsoft Store. In there `$ uname -r` command outputs "5.10.102.1-microsoft-standard-WSL2".
> This makes _isWsl()_ function to return `false` in such environments and breaks JDK builds on WSL.
> 
> To correct that I made the substring search case-insensitive.

Marked as reviewed by erikj (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/14413#pullrequestreview-1475693626