move default configuration to common bin/include folder

move default configuration to common bin/include folder

Two programs need to be able to provide the effective configuration:
named (through a future rndc command) and named-checkconf (though a
future command line switch). In order to calculate the effective
configuration from named-checkconf, the default configuration
needs to be accessible.

The default configuration has now been moved from bin/named/config.c
into a common include directory for binaries: bin/include/defaultconfig.h.