I propose to remove --enable-ctrls from Makefile or make it configurable via OPTIONS.
I don't use this module but it cannot be disabled in configuration (or I cannot find how) but it emits error on each (re)start of ProFTPd:
proftpd: mod_ctrls/0.9.5: error: unable to bind to local socket: Address already in use
Really annoying if one does not need this functionality to be enabled.
This is the part of a Makefile which should be changed