[Bug libstdc++/16612] empty basic_strings can't live in shared memory

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=16612
Bug 16612 depends on bug 24882, which changed state.

Bug 24882 Summary: [meta-bug] Non-refcounted, moveable basic_string
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24882

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