'RELENG_6_0_0_RELEASE'.

This commit was manufactured to restore the state of the 6.0-RELEASE image.

use main() to do it locally.

o Old-style K&R declarations have been converted to new C89 style
o register has been removed
o prototype for main() has been removed (gcc3 makes it an error)
o int main(int argc, char *argv[]) is the preferred main definition.
o Attempt to not break style(9) conformance for declarations more than
  they already are.
o gc some #ifdef sun ... #endif code

Approved by: arch@, new style(9)

o Add consts where appropriate.
o Rename some variables that were shadowing global declarations.
o Remove register storage-classes.
o Make errmsg a const, so we can just set error messages instead
  of using sprintf/strcpy.
o Set WARNS=2

Reviewed by:	bde, des

error caused by the -1 being on the wrong side of the comparison.
This would not cause an overflow, as near as I can tell, because we
truncate later anyway.  We'd just fail to get a diagnostic for 1024
and 1025 byte file names.