New AIX libstdc++ testsuite failures - visibility

[David Edelsohn]

	Something has changed in the past day to introduce a huge number
of new libstdc++ testsuite failures on AIX all complaining about
visibility.  I do not know if this is due to a libstdc++ change or the PRE
changes.  The failures look like:

src/libstdc++-v3/testsuite/23_containers/deque/check_construct_destroy.cc:80: warning: visibility attribute not supported in this configuration; ignored

src/libstdc++-v3/testsuite/23_containers/deque/cons/1.cc:49: warning: visibility attribute not supported in this configuration; ignored

src/libstdc++-v3/testsuite/23_containers/deque/cons/2.cc:520: warning: visibility attribute not supported in this configuration; ignored

src/libstdc++-v3/testsuite/23_containers/deque/modifiers/swap/2.cc:132: warning: visibility attribute not supported in this configuration; ignored

etc.

	Any idea what is going on?

Thanks, David