The newlib "team" rolls new releases about once a year (december).
This is quite a long time between releases, in case code was fixed.
So, allow user to use a CVS snapshot to benefit early from fixes
and enhancements to newlib.
newlib handles the build/host/target a bit differently as one would expect:
build : not used
host : the nachine that builds newlib
target : the machine on which newlib will run
