and minor fixes:
. add ack/clean target to lib, 'unify' clean target
. add includes as library dependency
. mk: exclude warning options clang doesn't have in non-gcc
. set -e in lib/*.sh build files
. clang compile error circumvention (disable NOASSERTS for release builds)
this is to force invocations of these utils for ack to be
explicitly named such, so in the future binutils can be installed
in /usr/pkg without the g- prefix.
