The change is currently needed to be able to remove the board
configuration scripting from the top level Makefile and replace it by
a simple, table driven script.
Moving this configuration setting into the "CONFIG_*" name space is
also desirable because it is needed if we ever should move forward to
a Kconfig driven configuration system.
Signed-off-by: Wolfgang Denk <wd@denx.de>
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.
