gcc: fix to provide same settings we use for -m{arch,cpu,tune} via configure options
gcc 4.4 introduced configure options for arch, cpu and tune which influence
the default compiler settings on the final target machine.
Because we inject -m{arch,cpu,tune} through the gcc wrapper we now have to
provide the same settings through configure options, so the final user is
not running into problems like getting missing symbols for software
emulated facilities provided by the gcc support library.