Canonicalise CT_BUILD and CT_HOST:

- Not only will it give us full-qualified tuples, but it will also ensure
that they are valid tuples (in case of typo with user-provided tuples)
That's way better than trying to rewrite config.sub ourselves...
- use CT_BUILD_PREFIX and CT_BUILD_SUFFIX to call "gcc -dumpmachine"

/trunk/scripts/crosstool.sh | 29 7 22 0 +++++++----------------------
1 file changed, 7 insertions(+), 22 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