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>

diff --git a/mpz/remove.c b/mpz/remove.c

--- a/mpz/remove.c

+++ b/mpz/remove.c

@@ -23,7 +23,7 @@

 unsigned long int

 mpz_remove (mpz_ptr dest, mpz_srcptr src, mpz_srcptr f)

 {

-  mpz_t fpow[40];		/* inexhaustible...until year 2020 or so */

+  mpz_t fpow[GMP_LIMB_BITS];		/* Really MP_SIZE_T_BITS */

   mpz_t x, rem;

   unsigned long int pwr;

   int p;

@@ -69,7 +69,7 @@

       mpz_set (dest, x);

     }

-  pwr = (1 << p) - 1;

+  pwr = (1L << p) - 1;

   mpz_clear (fpow[p]);

diff --git a/mpz/remove.c b/mpz/remove.c

--- a/mpz/remove.c

+++ b/mpz/remove.c

@@ -80,7 +80,7 @@

       mpz_tdiv_qr (x, rem, dest, fpow[p]);

       if (SIZ (rem) == 0)

 	{

-	  pwr += 1 << p;

+	  pwr += 1L << p;

 	  mpz_set (dest, x);

 	}

       mpz_clear (fpow[p]);