crunchgen(1): Support building and linking internal libraries

crunchgen(1): Support building and linking internal libraries

Some programs (e.g., grep, diff, telnet) use internal libraries.  In
order to crunch such programs, the corresponding internal libraries
must be built together with the programs and then are used to create
the <progname>.lo.

Extend the crunchgen(1)'s "special" command by adding the "lib_int"
keyword, which specifies the internal libraries to be used to create
the <progname>.lo.

The "libs_int" command is also implemented to support building the
needed internal libraries which will be statically linked to create
the final crunched executable.