The function make_relative_prefix_1 does not properly free locally
allocated memory when it returns early.

Free the memory associated with the variables full_programe, bin_dirs,
prog_dirs, and prefix_dirs when the function returns early.

Submitted by: Tom Rix <trix@juniper.net>
Reviewed by: jhibbits, emaste
Approved by: sjg (mentor)
Obtained from: Juniper Networks, Inc.
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9691