scripts/crosstool-NG.sh.in: On MacOS/BSD use the output of CT_DoConfigGuess for CT_BUILD.

On 64bit MacOS `gcc -dumpmachine` gives i686 for the host machine.
This conflicts with the expectations of some following configure scripts
that a 64bit x86 is given as x86_64; i686 is understood as a 32 bit machine.
config.guess sets the host machine in CT_BUILD correctly.

yann.morin.1998@anciens.enib.fr:
As suggested by Khem RAJ on the ML, always use config.guess.

 #!/bin/sh

 canonicalizedname=$(readlink -nm "${0}")

 dirname="$(dirname "${canonicalizedname}")"

 basename="$(basename "${canonicalizedname}")"

 ld_lib_path="$(dirname "${dirname}")/lib"

 case ":${LD_LIBRARY_PATH}:" in

     *":${ld_lib_path}:"*)   ;;

     *)  LD_LIBRARY_PATH="${ld_lib_path}${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}";;

 esac

 export LD_LIBRARY_PATH

 exec "${dirname}/.${basename}" "$@"