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(-)

 --- gcc-4.0.0/libstdc++-v3/include/c_std/std_cstdio.h-orig	2005-04-29 00:08:41.000000000 -0500

 +++ gcc-4.0.0/libstdc++-v3/include/c_std/std_cstdio.h	2005-04-29 00:08:45.000000000 -0500

 @@ -142,7 +142,7 @@

    using ::vsprintf;

  }

 -#if _GLIBCXX_USE_C99

 +#if _GLIBCXX_USE_C99 || defined(__UCLIBC__)

  #undef snprintf

  #undef vfscanf