POSIXify ./configure, and comment some parts of it.
Thanks to Martin GUY for pointing out that ./configure was not POSIXly correct.

/trunk/configure | 51 35 16 0 +++++++++++++++++++++++++++++++++++----------------
1 file changed, 35 insertions(+), 16 deletions(-)

# ia64 specific config options

config ARCH_ia64

    select ARCH_SUPPORTS_BOTH_ENDIAN

    help

      The ia64 architecture, as defined by:

        http://www.intel.com/design/itanium/arch_spec.htm