git: openjdk/jdk: 8309287: Add fontconfig requirement to building.md for Debian

[Yuri Nesterenko]

Changeset: 73e7af9e
Author:    Jan Kratochvil <jkratochvil at openjdk.org>
Committer: Yuri Nesterenko <yan at openjdk.org>
Date:      2023-06-02 08:41:28 +0000
URL:       https://git.openjdk.org/jdk/commit/73e7af9e28805dda25f91fd509e3860d8586ad9f

8309287: Add fontconfig requirement to building.md for Debian

Reviewed-by: erikj

! doc/building.html
! doc/building.md