Speed up font database loading with fontconfig

Trust fontconfig if it claims that the font supports a language
and don't use the expensive check for a symbol font in this case.
Speeds up app startup if the system has many latin only fonts
installed by a big amount.

Also remove some compat handling for fontconfig versions from
2003 and earlier... :)

Change-Id: I5de0812685ae76090b2c0ef5b6c2dcf430249bb8
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>