RFR: 8323700: Add fontconfig requirement to building.md for Alpine Linux [v2]

[Magnus Ihse Bursie]

On Mon, 15 Jan 2024 06:18:28 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

>> Similar to JDK-8309287.
>
> Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update doc/building.html

Marked as reviewed by ihse (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/17415#pullrequestreview-1821464384