Add support for a saving build objects in a separate directory. ...

Modifications are based on the linux kernel approach and
support two use cases:

  1) Add O= to the make command line
  'make O=/tmp/build all'

  2) Set environement variable BUILD_DIR to point to the desired location
  'export BUILD_DIR=/tmp/build'
  'make'

The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'

Command line 'O=' setting overrides BUILD_DIR environent variable.

When none of the above methods is used the local build is performed and
the object files are placed in the source directory.

* Implement new mechanism to export U-Boot's functions to standalone ...

applications: instead of using (PPC-specific) system calls we now
  use a jump table; please see doc/README.standalone for details

* Patch by Dave Westwood, 24 Jul 2003:
  added support for Unity OS (a proprietary OS)

* Code cleanup: ...

- remove trailing white space, trailing empty lines, C++ comments, etc.
  - split cmd_boot.c (separate cmd_bdinfo.c and cmd_load.c)

* Patches by Kenneth Johansson, 25 Jun 2003:
  - major rework of command structure
    (work done mostly by Michal Cendrowski and Joakim Kristiansen)

* Patch by Thomas Frieden, 13 Nov 2002: ...

Add code for AmigaOne board
  (preliminary merge to U-Boot, still WIP)

* Patch by Jon Diekema, 12 Nov 2002:
  - Adding URL for IEEE OUI lookup
  - Making the autoboot #defines dependent on CONFIG_AUTOBOOT_KEYED
    being defined.
  - In the CONFIG_EXTRA_ENV_SETTINGS #define, the root-on-initrd and
    root-on-nfs macros are designed to switch how the default boot
    method gets defined.