The bash builtin versions of the "test" (resp. "[") command allow
using "==" for string comparisons, but POSIX compatible implemen-
tations (like /usr/bin/test) insist on using "=" only. On such systems
you will see:

	$ /usr/bin/test a == a && echo OK
	/usr/bin/test: ==: binary operator expected

This patch fixes Makefiles and scripts to use POSIX style.

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.

cpu_reset code from cpu/$(CPU) into the new cpu/$(CPU)/$(SOC) directories
Patch by Andreas Engel, 13 Mar 2006

sed the linker scripts, rather than pre-process them.
Patch by Peter Pearse, 07 Oct 2005

Use lowlevel_init() instead of platformsetup() [rename].
Patch by Peter Pearse, 06 Oct 2005