On Darwin, shared modules and shared libraries are not interchangable
and since we preload sudo_noexec.so via DYLD_INSERT_LIBRARIES it
must be a library, not a module. We must relax the requirement
that libraries begin with a "lib" prefix to work around this
difference. This does mean you must use sudo's libtool on Darwin
(macOS) but that is already a requirement on other systems (notably
HP-UX and SCO) due to a number of libtool patches we require that
haven't be accepted upstream. This is a different fix for PR #102.