cogl: add missing colon in headers

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit fa2f47059cb94f7ff4601f7d5d8692f71abb0c21)
quaternion: fix structure introspection annotation

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 9cbf1e8a08fe0984f124f7447c5398e78a9019b4)
pipeline: fix method description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit cf3a12f28232389cdc11dd4fff23448071fa4b51)
texture-2d-sliced: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 015d928be5a791bbaf7385bac1cd07c900c41bbf)
texture-rectangle: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 58a52518680d57df18e7c896904d72d3bce21a11)
atlas-texture: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 4e11b784f07eeeb5a5c576915315637a2f09ae34)
attribute: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 31246d418f09989fda57c1511c91349fb0840b9c)
glib-source: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit f3c930ceb71a141ac34c857b0adfbe498b876fe9)