Simplify QFontDatabase::load() a bit

Change-Id: Iaf7db1eb542db1ea0f2ca6c83282961bf4341243
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Haiku: Add support for Haiku to build system

Change-Id: I12afaeb53a7f35c3f02776d28dad96107f3c5819
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Augustin Cavalier <waddlesplash@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>