aklog: Use a function to print debug statements

aklog: Use a function to print debug statements

aklog was scattered with things like
    if (dflag) {
	printf("Oh no, the world is ending\n");
    }

Simplify these by adding a dprintf() function, which only prints its
arguments if dflag is defined. Use this throughout the code.

Change-Id: I673942e9ea6a8b96ea9d11a608cfaeaf00098b88
Reviewed-on: http://gerrit.openafs.org/1324
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>