Convert make(1) to use ANSI style function declarations. Variable

Convert make(1) to use ANSI style function declarations.  Variable
documentation already adequatedly existed in the description in most
cases.  Where it did not, it was added.  If no documentation existed
beforehand, then none was added.  Some unused dummies for use in the
traversal functions were marked as __unused during the conversion.
Occasionally, local style fixes were applied to lines already being
modified or influenced.

Taken-from: FreeBSD/jmallett