Support new option --linuxdir to specify location of kernel source tree.
+ Use --with-linux{-obj} values from previous ./configure run.
+ Use --with-spl{-obj} values from previous ./configure run.
+ _configure was specified earlier, but never used. Use it!
Remove '-g -O2' when building zvol_id.
+ crashes on 64bit kernel with 32bit userland.
Add --keep-version to alien
+ So that not all packages end up with <version>-0.