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-4.2.1-stock/gcc/config/alpha/linux-unwind.h	2005-06-24 20:22:41.000000000 -0500

+++ gcc-4.2.1/gcc/config/alpha/linux-unwind.h	2007-09-01 20:21:34.000000000 -0500

@@ -29,6 +29,9 @@ Boston, MA 02110-1301, USA.  */

 /* Do code reading to identify a signal frame, and set the frame

    state data appropriately.  See unwind-dw2.c for the structs.  */

+/* Don't use this if inhibit_libc is set

+   The build for this target will fail trying to include missing headers */

+#ifndef inhibit_libc

 #include <signal.h>

 #include <sys/ucontext.h>

@@ -80,3 +83,4 @@ alpha_fallback_frame_state (struct _Unwi

   fs->retaddr_column = 64;

   return _URC_NO_REASON;

 }

+#endif /* inhibit_libc */