[build] Move gthr to toplevel libgcc

[Paolo Bonzini]

On 08/08/2011 03:47 PM, Rainer Orth wrote:
>
> This patch was bootstrapped without regressions on i386-pc-solaris2.10
> and i386-pc-solaris2.11.  It probably needs more testing on other
> non-posix platforms.

Did you include Ada?

Paolo