[Hexchat] Add font rendering patch

Summary:

• Added "Use pango_font_metrics_get_height() to calculate font height" patch. Upstream bug.

I did notice an improvement in font rendering with this patch applied while testing the now abandoned D10958, so I think it's deserving of being fixed. Notably chat seems less "smooshed" with a more natural spacing between lines.

Test Plan:

• Tested that Hexchat opened
• Checked that IRC was working
• Checked that font appeared to be rendering acceptably

Reviewers: Triage Team, JoshStrobl

Reviewed By: Triage Team, JoshStrobl

Subscribers: JoshStrobl, TClark77

Differential Revision: https://dev.getsol.us/D10963