Finish wrapping <netdb.h> so that calls go direct and the symbols are all weak

Move to the <limits.h> universe.
review by millert, binary checking process with doug, concept with guenther

Make the asr API public. Install asr.h to /usr/include.h and manpages.
Include tweaks suggested by mpi@

ok deraadt@

Cleanup and simplify the API to be exposed. Use better names for
structures, functions and defines.

discussed with and ok deraadt@ guenther@

Make some symbols static and prefix all visible symbols with asr_
to prevent collisions with third-party programs.

suggested by sthen@, ok theo@

use paramaters instead of static storage in _gethostbyname()

Add minimal support for _res setup and update.

Change res_init() to initialize the _res structure on first call, and
udpate the global async context if changes were made by the user. All
resolver fu

Add minimal support for _res setup and update.

Change res_init() to initialize the _res structure on first call, and
udpate the global async context if changes were made by the user. All
resolver functions now call res_init() internally.

fixes issue spotted by otto@

show more ...

spacing

use the provided ALIGN() macro instead of re-inventing a square wheel.

prodded by deraadt@

space cleanup; ok eric

fix alignment issue in the structure filled by gethostby{name,addr}()

spotted by naddy@

knf

split asr_resolver.c into different files to overlay the libc/net
resolver implementation.