patch 9.0.0287: Irix systems no longer exist

Problem:    Irix systems no longer exist.
Solution:   Remove references to Irix. (Yegappan Lakshmanan, closes #10994)
diff --git a/src/version.c b/src/version.c
index 2065483..bfa29ef 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    287,
+/**/
     286,
 /**/
     285,