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>

 --- gcc/gcc/config.gcc.uclibc100-sh~	2006-03-06 20:46:56 +0100

 +++ gcc/gcc/config.gcc	2006-03-10 15:02:41 +0100

 @@ -1905,7 +1905,7 @@

  	;;

  sh-*-elf* | sh[12346l]*-*-elf* | sh*-*-kaos* | \

  sh-*-symbianelf* | sh[12346l]*-*-symbianelf* | \

 -  sh-*-linux* | sh[346lbe]*-*-linux* | \

 +  sh*-*-linux* | sh[346lbe]*-*-linux* | \

    sh-*-netbsdelf* | shl*-*-netbsdelf* | sh5-*-netbsd* | sh5l*-*-netbsd* | \

     sh64-*-netbsd* | sh64l*-*-netbsd*)

  	tmake_file="${tmake_file} sh/t-sh sh/t-elf"