apachectl uses bindir instead of sbindir to look for envvars: you should change @exp_bindir@/envvars to @exp_sbindir@/envvars in lines 46 and 47 of ./support/apachectl.in
Thanks for your fix, and thanks for using Apache. I've committed the fix to Apache 2.1-dev and have also proposed that it be merged into the next 2.0.x release.