Require Harfbuzz only for Wayland and X11 backends.
Fixes #1968 (closed)
@fanc999 You didn't include Harfbuzz in your FT2 commit on Thursday. Should Win32 be in the list that turns on the Harfbuzz requirement?
Fixes #1968 (closed)
@fanc999 You didn't include Harfbuzz in your FT2 commit on Thursday. Should Win32 be in the list that turns on the Harfbuzz requirement?