This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
bsd.port.mk rev. 1.304 for details on the change.
The fix here is one of the following.
(1) Define USE_BZIP2 instead of BUILD_DEPENDS on bzip2 and redefining
EXTRACT_* commands.
(2) Change ${EXTRACT_CMD} to ${TAR} when the command is obviously
calling the "tar" command (i.e., arguments like "-xzf" are spelled
out).
(3) If ${EXTRACT_CMD} is called directly with ${EXTRACT_BEFORE_ARGS},
add ${EXTRACT_AFTER_ARGS} to the command line as well.
(4) If any of EXTRACT_CMD, EXTRACT_BEFORE_ARGS or EXTRACT_AFTER_ARGS
is set, define the other two too.
