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>

 2008-04-28  Hiroki Kaminaga  <kaminaga@sm.sony.co.jp>

 	[BZ 6740]

 	nptl/sysdeps/powerpc/tcb-offsets.sym (PRIVATE_FUTEX_OFFSET):

 	Guard sym definition with #ifndef __ASSUME_PRIVATE_FUTEX.

 --- a/nptl/sysdeps/powerpc/tcb-offsets.sym

 +++ b/nptl/sysdeps/powerpc/tcb-offsets.sym

 @@ -15,4 +15,6 @@

  PID				thread_offsetof (pid)

  TID				thread_offsetof (tid)

  POINTER_GUARD			(offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t))

 +#ifndef __ASSUME_PRIVATE_FUTEX

  PRIVATE_FUTEX_OFFSET		thread_offsetof (header.private_futex)

 +#endif