gcc-2.95pre rs6000-ibm-aix fix-header bug still present

[David Edelsohn]

	fix-header continues to generate extraneous definitions of
EXIT_FAILURE and EXIT_SUCCESS in stdlib.h on AIX systems.  This causes
numerous warnings that those macros are redefined whenever stdlib.h is
included in a file.

	Somehow fix-header is confused by AIX's stdlib.h and does not
record that those macros already are present in the original version of
the file. 

	Generating a "fixed" header file which produces warnings/errors
introduced by the fixing process should not be allowed to remain in the
release.

David