btrfs-progs: Correct value printed by assertions/BUG_ON/WARN_ON

btrfs-progs: Correct value printed by assertions/BUG_ON/WARN_ON

The values passed to BUG_ON/WARN_ON are negated(!) and printed, which
results in printing the value zero for each bug/warning. For example:
volumes.c:988: btrfs_alloc_chunk: Assertion `ret` failed, value 0

This is not useful. Instead changed to print the value of the parameter
passed to BUG_ON()/WARN_ON(). The value needed to be changed to long
to accomodate pointers being passed.

Also, consolidated assert() and BUG() into ifndef.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>