- Made the test in the packages produced by %update_kernel_modules_checkinstall
  not ignore the exit status of update-kernel.

- kernel-macros: added powerpc support to %base_arch macro.

- kernel-macros: made %setup_kernel_module automatically add
  the usual {,Build}Requires for kernel-modules-*.
- kernel-macros: added for possible use in modules:
  + %kimage & %requires_kimage;
  + %update_kernel_modules_checkinstall
    (to produce a specific kind of checkinstall subpkg);
  + %setup_kernel_module_from_globals (split from %setup_kernel_module) for
    those who want to set %kversion and %krelease manually, without rpmquery).