cmp: remove history comment. it is more natural to keep it in source control

cmp: remove history comment. it is more natural to keep it in source control

The comment was:

* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
*
* Original version majorly reworked for SUSv3 compliance, bug fixes, and
* size optimizations.  Changes include:
* 1) Now correctly distinguishes between errors and actual file differences.
* 2) Proper handling of '-' args.
* 3) Actual error checking of i/o.
* 4) Accept SUSv3 -l option.  Note that we use the slightly nicer gnu format
*    in the '-l' case.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>