#9862: On AIX PIPE_BUF is broken.  Make it 512.

Patch by Sébastien Sablé.
diff --git a/configure.in b/configure.in
index 01d81e9..4252d93 100644
--- a/configure.in
+++ b/configure.in
@@ -4213,6 +4213,10 @@
 ],
 [AC_MSG_RESULT(no value specified)])
 
+case $ac_sys_system in
+AIX*)   
+  AC_DEFINE(HAVE_BROKEN_PIPE_BUF, 1, [Define if the system reports an invalid PIPE_BUF value.]) ;;
+esac
 
 
 case $ac_sys_system in