RFR: 8317357: Update links in building.md to use https rather than http

[Iris Clark]

On Thu, 16 Nov 2023 17:09:25 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> From the bug report: Building.md file contains a number of HTTP links that would need to be converted to HTTPS in order for clicking on the links on the OpenJDK web site at https://openjdk.org/groups/build/doc/building.html to work. 
> 
> It is also best practice nowadays to always prefer https in links; most http requests are upgraded to https anyway.

Marked as reviewed by iris (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/16695#pullrequestreview-1735123412