[RT #1709]
Change isc_entropy_usebestsource() to have saner semantics:
- If an invalid file is specified, an error will be returned instead of the
keyboard being used.
- If no file is specified but a random device is present, the keyboard will
be used if there is an error opening the random device.
- ISC_ENTROPY_KEYBOARDYES indicates that the keyboard should be the
only device used. Otherwise, passing '-r keyboard' is meaningless
on a machine with a random device, since the keyboard will not be used.
Change the callers in the dnssec tools and rndc-confgen to check for the
special file "keyboard" and call isc_entropy_usebestsource() with the right set
of parameters.
'magic' was not being declared consistantly.
some #include <isc/magic.h> were missing from other include files.
NS_SERVER_VALID was not using ISC_MAGIC_VALID.
