Patch to update libtool in GCC and Src trees

[Paolo Bonzini]

> Looking at libtool.m4, it looks like the only difference between the
> libtool version and the standard version was in setting
> lt_cv_deplibs_check_method.  The orignal libtool.m4 has a case statement
> for "linux-gnu*" and the libtool one changed it to be
> "linux-gnu*|linux-newlib*".
> 
> The latest libtool just checks "linux*" so this local libtool.m4 change
> shouldn't be needed if newlib uses the latest libtool.

Agreed.  Sorry to take through another iteration.

1) First possibility is to first copy newlib's libtool.m4 onto src/gcc, 
and apply Chuck's suggested changes, at the same time.

2) Otherwise, we just update libtool in GCC and src trees, again 
including Chuck's suggested changes in the patch.

Jeff, what do you prefer?

Paolo