Hi build machinery maintainers,

since we always build the C++ compiler now, I fail to see the need to still
use RAW_CXX_TARGET_EXPORTS for libvtv.

The situation to expose the problem is:
* Use a multilib-enabled x86_64-linux box.
* Use a 64-bit (multilib-disabled) bootstrap compiler (binary image).
$ configure --enable-multilib --with-system-zlib
$ make bootstrap

When it comes to build the 32-bit libvtv, it breaks because of using
"CC=/build/prev-gcc/xgcc -m32" "CXX=g++ -m32", while it should use
"CC=/build/prev-gcc/xgcc -m32" "CXX=/build/prev-gcc/xg++ -m32" instead.

However, I'm not sure about the general question behind:
Should it work to bootstrap the multilib-compiler using a non-multilib one?

This also needs above configure flags to work around two more but minor issues,
which I'm unsure about whether I can/should fix at all:
* --enable-multilib: Without this, the "user friendly check" is breaking,
    since https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=205975
* --with-system-zlib: Without this, --enable-multilib tries to build a
    32-bit zlib with "CC=/build/32/./prev-gcc/xgcc"

Thanks!
/haubi/