changes for approval, part three (solaris)

[David Edelsohn]

	As I alluded to last night, few of the macros in _G_config.h are
used by libstdc++-v3, so inquiring correct values may not be necessary.
If _G_config.h is going to be synched with glibc at all, then auto-gen
will not work unless glibc will auto-gen the file as well.  Currently
glibc provides hand-tweaked _G_config.h in its sysdeps hierarchy.

	Removing the _G_config.h dependency from libio.h and forcing the
definitions of __P(), __PMT(), and __THROW which GCC 3.0 will provide
seems like a clean solution.  Current glibc pretty much depends on GCC 3.0
as well, so pushing the libio.h update back to glibc libio should not
cause any problems.

David