These are documented in --help and will be cached.
AC_PROG_YACC
AM_PATH_PYTHON(,,[:])
AC_PATH_PROG([PERL], [perl], [], [$PATH:/bin:/usr/bin:/usr/local/bin])
+AC_ARG_VAR([PERL], [the Perl interpreter])
AC_PATH_PROG([GPERF], [gperf], [], [$PATH:/bin:/usr/bin:/usr/local/bin])
+AC_ARG_VAR([GPERF], [the GNU gperf program])
# because gperf is not needed by end-users we just report it but do not abort on failure
AC_MSG_CHECKING([gperf version >= 3.0.0])