This adds support for mirroring the display output on two KMS
connectors.
This patch also checks for a number of environment variables that can
influence how KMS is configured. The following variables can be set:
COGL_KMS_MIRROR: If this is set to anything then Cogl will try and setup
two connectors with the same resolution so that onscreen frame buffers
can be mirrored.
COGL_KMS_CONNECTOR0: This can be set to an integer identifier for a
specific KMS connector id to use for the first output.
COGL_KMS_CONNECTOR0_MODE: Can be set to a mode name like "1024x768"
explicitly select what mode should be used for the first output.
If COGL_KMS_MIRROR is set then COGL_KMS_CONNECTOR1 and
COGL_KMS_CONNECTOR1_MODE can optionally be set to specify a connector id
and mode name for the second output.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
125c31a70b