Don't force building target GMP and MPFR when a native gdb is built. Rather,
add a config knob to configure the native gdb to use or not to use GMP and
MPFR; _this_config_knob_ will force building the target GMP and MPFR only if
turned on.

/trunk/scripts/build/debug/300-gdb.sh | 2 1 1 0 +-
/trunk/config/debug/gdb.in | 21 19 2 0 +++++++++++++++++++--
2 files changed, 20 insertions(+), 3 deletions(-)

 # Compute Alpha-specific values

 CT_DoArchValues () {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_ALPHA_VARIANT}"

     # The kernel ARCH:

     CT_KERNEL_ARCH=${CT_ARCH}

 }