sysutils/procenv: Update to 0.55

• Take MAINTAINER'ship
• reorder Makefile (portclippy)
• deleted patches:

files/patch-configure.ac
files/patch-src_platform_freebsd_platform-freebsd.h
because changes were included upstream

ChangeLog: https://github.com/jamesodhunt/procenv/blob/0.55/NEWS

Reviewed by: daniel.engberg.lists@pyret.net
Approved by: dbaio (mentor)
Differential Revision: https://reviews.freebsd.org/D29689