[cfe-commits] [patch] Add support for tooldir relative libstdc++

[Rafael Espindola]

The attached patch makes it possible to use a libstdc++ that is
installed in path relative to clang. The use for this is

*) gcc (and its libstdc++) are installed in /foo
*) clang is installed in /foo
*) mv /foo /bar

gcc will correctly find libstdc++, but clang will not.

This might be useful if generalized for other libraries, but the patch
is already a bit too big. The patch also makes the handling of
nobuiltininc a lot more similar to what is done for nostdinc.

Let me know if you want me to split the patch in two. One plumbing
patch to pass the tooldir and one patch that actually adds support for
libstdc++ in a tooldir relative directory.

Cheers,
-- 
Rafael Ávila de Espíndola