cc/gcc: add option to compile against static libstdc++, for gcc-4.4 and newer

Idea and know-how taken from CodeSourcery build script.

Normal build:
$ ldd arm-unknown-linux-uclibcgnueabi-gcc
linux-gate.so.1 => (0xb77f3000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0xb76e8000)
libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb75a1000)
libm.so.6 => /lib/i686/cmov/libm.so.6 (0xb757a000)
/lib/ld-linux.so.2 (0xb77f4000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0xb755c000)

CC_STATIC_LIBSTDCXX=y:
$ ldd arm-unknown-linux-uclibcgnueabi-gcc
linux-gate.so.1 => (0xb7843000)
libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb76e6000)
/lib/ld-linux.so.2 (0xb7844000)

I made CC_STATIC_LIBSTDCXX default=y since I think
it is always desirable.

Signed-off-by: Johannes Stezenbach <js@sig21.net>

# Compute x86-specific values

# This one really needs a little love! :-(

CT_DoArchTupleValues() {

    # Override the architecture part of the tuple:

    if [ "${CT_ARCH_64}" = "y" ]; then

        CT_TARGET_ARCH=x86_64

    else

        arch="${CT_ARCH_ARCH}"

        [ -z "${arch}" ] && arch="${CT_ARCH_TUNE}"

        case "${arch}" in

            "")                           CT_TARGET_ARCH=i386;;

            i386|i486|i586|i686)          CT_TARGET_ARCH="${arch}";;

            winchip*)                     CT_TARGET_ARCH=i486;;

            pentium|pentium-mmx|c3*)      CT_TARGET_ARCH=i586;;

            pentiumpro|pentium*|athlon*)  CT_TARGET_ARCH=i686;;

            *)                            CT_TARGET_ARCH=i586;;

        esac

    fi

}