update variable-arguments documentation in README.Portability

[Matt Kraai <kraai at alumni dot cmu dot edu>]

Howdy,

README.Portability does not document the new method of handling
variable-argument function using VA_OPEN, VA_FIXEDARG, and
VA_CLOSE.  The following patch updates it.

OK to commit?

Matt

	* README.Portability (Function prototypes): Document new
	variable-argument function macros.

Index: gcc/README.Portability
===================================================================
RCS file: /cvs/gcc/gcc/gcc/README.Portability,v
retrieving revision 1.6
diff -c -3 -r1.6 README.Portability
*** gcc/README.Portability	16 Jul 2000 13:35:23 -0000	1.6
--- gcc/README.Portability	1 Jul 2002 19:01:43 -0000
***************
*** 139,170 ****
  
  void
  cpp_ice VPARAMS ((cpp_reader *pfile, const char *msgid, ...))
! {  
! #ifndef ANSI_PROTOTYPES
!   cpp_reader *pfile;
!   const char *msgid;
! #endif
!   va_list ap;
!   
!   VA_START (ap, msgid);
!   
! #ifndef ANSI_PROTOTYPES
!   pfile = va_arg (ap, cpp_reader *);
!   msgid = va_arg (ap, const char *);
! #endif
  
    ...
!   va_end (ap);
  }
  
! For the curious, here are the definitions of the above macros.  See
! ansidecl.h for the definitions of the above macros and more.
! 
! #define PARAMS(paramlist)  paramlist  /* ISO C.  */
! #define VPARAMS(args)   args
! 
! #define PARAMS(paramlist)  ()         /* K+R C.  */
! #define VPARAMS(args)   (va_alist) va_dcl
  
  One aspect of using K+R style function declarations, is you cannot
  have arguments whose types are char, short, or float, since without
--- 139,154 ----
  
  void
  cpp_ice VPARAMS ((cpp_reader *pfile, const char *msgid, ...))
! {
!   VA_OPEN (ap, msgid);
!   VA_FIXEDARG (ap, cpp_reader *, pfile);
!   VA_FIXEDARG (ap, const char *, msgid);
  
    ...
!   VA_CLOSE (ap);
  }
  
! See ansidecl.h for the definitions of the above macros and more.
  
  One aspect of using K+R style function declarations, is you cannot
  have arguments whose types are char, short, or float, since without

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