[Bug target/63773] [meta-bug] Restoring darwin bootstrap for gcc 5.0

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63773
Bug 63773 depends on bug 64023, which changed state.

Bug 64023 Summary: [5 Regression] r216964 breaks bootstrap on darwin when using gcc as the bootstrap compiler.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64023

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED