Rewrite gamma-randr to use gamma-common

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Rewrite gamma-vidmode to use gamma-common

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Rewrite gramma-drm to use gamma-common

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Rewrite gamma-w32gdi to use gamma-common

Signed-off-by: Mattias Andrée <maandree@operamail.com>