cad/pcb: Update 4.2.0 => 4.3.0

Changelogs:

• https://sourceforge.net/projects/pcb/files/pcb/pcb-4.3.0/

• Add LICENSE_FILE
• Replace dead WWW link
• Pet portclippy(1) and portfmt(1)

Approved by: hrs@ (maintainer, timeout > 4 years)
Approved by: yuri@ (Mentor)
PR: 255063
Differential Revision: https://reviews.freebsd.org/D53236