This patch improves the relability of harfbuzz and freetype builds by:
- harfbuzz-no-cairo, harfbuzz: explicitly requiring meson to find freetype.
- freetype-no-harfbuzz, freetype: explicitly disabling the optional brotli dependency, which is not included in any moduleset. This reduces the chances of the build failing in case the user has brotli installed outside of the jhbuild prefix.