roadmap: describe glibc commands.

Some glibc commands are irrelevant because they're for functionality
that is excluded from musl (mtrace, rpc*, localedef, iconvconfig, nscd).
getconf and catchsegv look like candidates for the development toolchain;
locale and iconv were already triaged.
getent is pretty lame, but it and the timezone stuff (tzselect zic
zdump) are the only new possibly interesting commands.
8 files changed