Simplify compression code.

• Remove the compression suffix macros and move them directly into the compress_type array.
• Remove the hardcoded sizes on the suffix and compression args arrays.
• Simplify the compression args arrays at the expense of a __DECONST when calling execv().
• Rewrite do_zipwork. The COMPRESS_* macros can directly index the compress_types array, so the outer loop is not needed. Convert fixed-length strings into asprintf or sbuf calls.

Submitted by: Dan Nelson <dnelson_1901@yahoo.com>
Reviewed by: gad
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D16518