0530 snap: rs6000-aix4.2.0.0 genattr Seg. Viol.

[Rodney Brown <rdb at localhost>]

Kaveh has reported build failures on rs6000-ibm-aix4 since CVS 0516.
genattr core dumps in stage2 without giving a useful backtrace in gdb.

Debugging (and from memory) it appears that the core dump is happening
on the switch statement in gcc/rtl.c:read_skip_spaces, if I remember
rightly, on the bctr instruction.
gcc/rtc.c from the 0530 snapshot has a date of 0422.
Will compare assembly between 0501 snapshot and 0530

/* Read chars from INFILE until a non-whitespace char
   and return that.  Comments, both Lisp style and C style,
   are treated as whitespace.
   Tools such as genflags use this function.  */
                                                    
int                                                                      
read_skip_spaces (infile)                        
     FILE *infile;                                              
{
  register int c;                  
  while (1)
    {                                                                  
      c = getc (infile);                       
      switch (c)
        {