V3 vs. AIX

[David Edelsohn]

	We need -berok, at least for some shared libraries, because
GNU/Linux developers have a habit of not listing all dependencies when
creating a shared library.  They assume that the main application's
dependency on the library and other SysV semantics will handle it when the
library actually is used at runtime.

	The AIX linker -G flag for creating SysV-style shared objects
already enables -berok by default.  When creating AIX-style shared
libraries, such as we are trying to create with libstdc++-v3, I do not see
a purpose for -berok.

	Unfortunately I cannot find the email where I was given
justification for retaining -berok in all modes.  I vaguely remember a
discussion about this with Alexandre, so maybe he will remember, but I
could be misattributing the discussion.

David