Ryan Schmidt authored Aug 27, 2018 and Philip Withnall committed Aug 31, 2018

The behavior of "which" is not standardized by POSIX. Some old
implementations print their error messages to stdout instead of stderr,
and don't return a nonzero exit code when they fail to find the given
program. "command -v" on the other hand is in POSIX (optional in 2004
and required as of 2008).

Remove otherwise-unused variables AUTORECONF and GTKDOCIZE.