package/pango: fix fontconfig meson option

Fixes:
output/build/pango-1.48.10/meson.build:1:0: ERROR: Unknown options: "use_fontconfig"

(WARNING for now, but will be an error in meson 0.60.0).

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Reviewed-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>