Remove obsolete IRIX checks (#12737)

IRIX is a discontinued and closed-source OS with last release in 2006.

TSRM/threads.m4

@@ -46,8 +46,6 @@ AC_DEFUN([PTHREADS_FLAGS],[
     PTHREAD_FLAGS=-D_REENTRANT;;
   *aix*)
     PTHREAD_FLAGS=-D_THREAD_SAFE;;
-  *irix*)
-    PTHREAD_FLAGS=-D_POSIX_THREAD_SAFE_FUNCTIONS;;
   *hpux*)
     PTHREAD_FLAGS=-D_REENTRANT;;
   *sco*)

ext/odbc/config.m4

@@ -14,7 +14,6 @@ AC_DEFUN([PHP_ODBC_FIND_SOLID_LIBS],[
   case $ac_solid_uname_s in
     AIX) ac_solid_os=a3x;;   # a4x for AIX4/ Solid 2.3/3.0 only
     HP-UX) ac_solid_os=h9x;; # h1x for hpux11, h0x for hpux10
-    IRIX) ac_solid_os=irx;;  # Solid 2.3(?)/ 3.0 only
     Linux)
       if ldd -v /bin/sh | grep GLIBC > /dev/null; then
         AC_DEFINE(SS_LINUX,1,[Needed in sqlunix.h ])

sapi/cgi/config9.m4

@@ -18,7 +18,7 @@ if test "$PHP_CGI" != "no"; then
 
     AC_MSG_CHECKING([whether cross-process locking is required by accept()])
     case "`uname -sr`" in
-      IRIX\ 5.* | SunOS\ 5.* | UNIX_System_V\ 4.0)
+      SunOS\ 5.* | UNIX_System_V\ 4.0)
         AC_MSG_RESULT([yes])
         AC_DEFINE([USE_LOCKING], [1],
           [Define if cross-process locking is required by accept()])