Rationalise ./configure
- borrow a lot of ideas from Michael ABBOTT ( http://sourceware.org/ml/crossgcc/2008-12/msg00030.html )
- should be conforming to POSIX 1003.1-2008, non compliance due to bashsims is to be considered a bug
- as a result, it now works with dash
- make a little easier to read in some places
- enforce 4-space indentation
- get rid of futile 'return $?'
- quote all variables assignments
- save and restore IFS prior to and after using alternate values
- simplify the TOOLS_TO_CHECK listing

What's left:
- provide a mean to actually _compare_ version numbers
- change the TOOLS_TO_CHECK pattern style to be able to use '|' in regexp

/trunk/configure | 243 127 116 0 ++++++++++++++++++++++++++++++++------------------------------
1 file changed, 127 insertions(+), 116 deletions(-)

# x86_64 specific options

config ARCH_x86_64

    select ARCH_64

    select ARCH_SUPPORT_ARCH

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    help

      The x86_64 architecture, as defined by:

        http://www.amd.com/us-en/Processors/DevelopWithAMD/0,,30_2252_875_7044,00.html