lib: add #include "foo.h" lines like in manpages

Should help in alleviating the header mess we have atm.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/igt_debugfs.c

@@ -39,6 +39,8 @@
  * @short_description: Support code for debugfs features
  * @title: i-g-t debugfs
  *
+ * > #include "igt_debugfs.h"
+ *
  * This library provides helpers to access debugfs features. On top of some
  * basic functions to access debugfs files with e.g. igt_debugfs_open() it also
  * provides higher-level wrappers for some debugfs features