Patch submitted by Paul Hargrove to fix NetBSD compile with -laio.

NetBSD puts the AIO functions in -lrt, vs. the usual libc.  So we
need the fbtl/posix configure.m4 to test for -lrt properly.

Reviewed by Jeff Squyres.

cmr=v1.7.4:reviewer=ompi-rm1.7:subject=Fix NetBSD use of -laio

This commit was SVN r30274.

ompi/mca/fbtl/posix/configure.m4

@@ -10,7 +10,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2012 The Regents of the University of California.
 #                         All rights reserved.
-# Copyright (c) 2010      Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2010-2014 Cisco Systems, Inc.  All rights reserved.
 # Copyright (c) 2008-2011 University of Houston. All rights reserved.
 # $COPYRIGHT$
 # 
@@ -25,9 +25,11 @@
 AC_DEFUN([MCA_ompi_fbtl_posix_CONFIG],[
     AC_CONFIG_FILES([ompi/mca/fbtl/posix/Makefile])
 
+    fbtl_posix_happy=no
     AC_CHECK_HEADER([aio.h],
-                    [fbtl_posix_happy="yes"],
-                    [fbtl_posix_happy="no"])
+                    [dnl NetBSD has aio_* in -lrt, vs. the usual libc
+                     OMPI_CHECK_FUNC_LIB([aio_write], [rt],
+                                         [fbtl_posix_happy="yes"])])
 
     AS_IF([test "$fbtl_posix_happy" = "yes"],
           [$1],