Remove getaddrinfo and freeaddrinfo from the Libc::Plugin and get rid of
the extra libc_resolv library. Remove getaddrinfo/freeaddrinfo symbol
hiding patch for FreeBSD sources. Remove libc_resolv from Makefiles and
run scenarios.
Fix#2273
The files are generated via flex and bison. Until now, this step was
performed when preparing the libc port. Unfortunately, the generated
files have subtle differences depending on the flex/bison versions
installed in the host. For example, the bison version number appears in
the generated code. This, in turn, breaks the hash mechanism of the
depot where a src/libc archive ends up being slightly different when
created on different hosts.
By moving the code generation to the build stage, the src/libc archive
merely contains the nslexer.l and nsparser.y source files but not the
generated files.
