demangle.h (demangle<Allocator>::symbol(char const*)): Decode symbols that start with _GLOBAL_[ID]_ differently...

* include/bits/demangle.h (demangle<Allocator>::symbol(char const*)):
Decode symbols that start with _GLOBAL_[ID]_ differently: the
trailing part ends with a terminating zero and is not necessarily an
encoding.
* src/demangle.cc (): Same.
* testsuite/demangle/regression/cw-13.cc: Adjust for new output.

From-SVN: r72027