Delete old info about Irix.

etc/MACHINES

@@ -755,25 +755,13 @@ Iris 2500 and Iris 2500 Turbo (m68k-sgi-iris3.5 or m68k-sgi-iris3.6)
 
 Iris 4D (mips-sgi-irix[456].*)
 
+  Emacs 21.3 is reported to work on IRIX 6.5.x.
+
   You can build a 64-bit executable (with larger maximum buffer size)
   on Irix 6.5 by specifying the 64-bit ABI using the `-64' compiler
   flag or otherwise (see cc(1)).  This may work on earlier Irix 6
   systems if you edit src/s/irix6-0.h following irix6-5.h.
 
-  Building Emacs 21.1 and 21.2 on versions of Irix before 6.5.10,
-  especially when Emacs is built with GCC, was reported to have subtle
-  problems such as being unable to print to stdout under the -batch
-  command-line option.  Building with the native compiler or upgrading
-  the OS to a newer version solves these problems.  There's evidence
-  that these problems are actually related to the runtime libraries
-  (before IRIX 6.5.10, the IRIX runtimes were based on the MIPSpro 7.2
-  compilers), so installing patches for the runtime from
-  http://www.sgi.com/support/patch_intro.html could solve the problem
-  even without upgrading the OS.  The dump process is the crucial
-  step that needs the upgraded runtime, so a workaround is to dump
-  Emacs on a machine with a newer OS, then copy the binary to the
-  older OS.
-
   If compiling with GCC on Irix 6 yields an error "conflicting types
   for `initstate'", install GCC 2.95 or a newer version, and this
   problem should go away.  It is possible that this problem results
@@ -781,23 +769,6 @@ Iris 4D (mips-sgi-irix[456].*)
   could also try reinstalling the same version of GCC, and telling us
   whether that fixes the problem.
 
-  The 19.26 pretest was reported to work on IRIX 4.0.5 and 5.2.
-  19.23 was reported to work on IRIX 5.2, but you may need to install
-  the "compiler_dev.hdr.internal" subsystem in order to compile unexelfsgi.c.
-  19.22 was known to work on all Silicon Graphics machines running
-  IRIX 4.0.5 or IRIX 5.1.
-
-  Compiling with -O using IRIX compilers prior to 3.10.1 may not work.
-  Don't use -O or use GCC instead.
-
-  Most IRIX 3.3 systems do not have an ANSI C compiler, but a few do.
-  Compile Emacs 18 with the -cckr switch on these machines.
-
-  There is a bug in IRIX 3.3 that can sometimes leave ptys owned by root
-  with a permission of 622.  This causes malfunctions in use of
-  subprocesses of Emacs.  Irix versions 4.0 and later with GNU Emacs
-  versions 18.59 and later fix this bug.
-
 Masscomp (m68k-masscomp-rtu)
 
   18.36 worked on a 5500DP running RTU v3.1a and compiler version 3.2