sync'd with lib makefile changes: use var for awk; fixed RECV* / SEND* defines; debug var can be overwritten; added better compiler path handling.

ares_getopt() command-line parser function does not belong to actual c-ares library. It is just a convinience source code helper function for use in example programs adig.c and ahost.c

as appropriate for platforms that don't have autotools support

use correct version var.

added generation of config.h and a prebuild target to create all neded files.