cc/gcc: fix C++ headers location

In case we build the C++ compiler, we have to tell gcc where to put the C++
headers, or else it will try to # put it in prefix/tuple/include, which we
make a symlink to sysroot/usr/include during the build, and that we delete
(the symlink!) after the build, but gcc will not look in sysroot/usr/inlcude
for C++ headers by default.

Implements a fix suggested by: Bryan Hundven <bryanhundven@gmail.com>

Reported-by: Anthony Foiani <anthony.foiani@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from a0924619112015bdaa81a0a2313d21ef38607bc2)

diff -durN gcc-4.2.1.orig/gcc/config.gcc gcc-4.2.1/gcc/config.gcc

--- gcc-4.2.1.orig/gcc/config.gcc	2007-02-03 06:25:20.000000000 +0100

+++ gcc-4.2.1/gcc/config.gcc	2007-08-03 20:29:52.000000000 +0200

@@ -1964,7 +1964,7 @@

         ;;

 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"