Small documentation fixes. Fixes #523978.

Original commit message from CVS:
Patch by: Mark Nauwelaerts <manauw at skynet be>
* gst/gstclock.h:
* libs/gst/base/gstbasesrc.h:
* libs/gst/base/gstbasetransform.c:
* libs/gst/check/gstcheck.c:
Small documentation fixes. Fixes #523978.
5 files changed