[Bug debug/61352] gcc 4.9.0 fails to execute dsymutil when linking executables on darwin

[howarth.at.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61352

--- Comment #11 from Jack Howarth <howarth.at.gcc at gmail dot com> ---
fix confirmed when applied to gcc 4.9.0.