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>

# Build script for libtool

CT_LIBTOOL_VERSION=2.2.6b

do_companion_tools_libtool_get() {

    CT_GetFile "libtool-${CT_LIBTOOL_VERSION}" \

               {ftp,http}://ftp.gnu.org/gnu/libtool

}

do_companion_tools_libtool_extract() {

    CT_Extract "libtool-${CT_LIBTOOL_VERSION}"

    CT_Patch "libtool" "${CT_LIBTOOL_VERSION}"

}

do_companion_tools_libtool_build() {

    CT_DoStep EXTRA "Installing libtool"

    mkdir -p "${CT_BUILD_DIR}/build-libtool"

    CT_Pushd "${CT_BUILD_DIR}/build-libtool"

    CT_DoExecLog ALL \

    "${CT_SRC_DIR}/libtool-${CT_LIBTOOL_VERSION}/configure" \

        --prefix="${CT_TOOLS_OVERIDE_DIR}"

    CT_DoExecLog ALL make

    CT_DoExecLog ALL make install

    CT_Popd

    CT_EndStep

}