Remove all generated files in "make clean"
Remove all generated files in "make clean"

Most of the generated files are named as 'tmp-*', and others all have
'AUTO-GENERATED FILE' in the header

While sys-zlib.h was initialially generated, but it has been manually
modified since, so do not remove it.

kealist/ren-c,codebybrett/ren-c,draegtun/ren-c,codebybrett/ren-c,rgchris/ren-c,rgchris/ren-c,giuliolunati/ren-c,rgchris/ren-c,hostilefork/rebol,kealist/ren-c,codebybrett/ren-c,codebybrett/ren-c,giuliolunati/ren-c,hostilefork/rebol,kealist/ren-c,draegtun/ren-c,draegtun/ren-c,giuliolunati/ren-c,hostilefork/rebol,kealist/ren-c,hostilefork/rebol,draegtun/ren-c,kealist/ren-c,draegtun/ren-c,hostilefork/rebol,rgchris/ren-c,rgchris/ren-c,giuliolunati/ren-c,codebybrett/ren-c,codebybrett/ren-c,draegtun/ren-c,kealist/ren-c,hostilefork/rebol,giuliolunati/ren-c