config/ompi_check_lustre.m4: respect the --without-lustre flag

make sure we actually respect if the user set the --without-lustre
flag (instead of continuing in the m4 macro as was the case until now).

Signed-off-by: Edgar Gabriel <egabriel@central.uh.edu>

config/ompi_check_lustre.m4

@@ -11,7 +11,7 @@ dnl                         University of Stuttgart.  All rights reserved.
 dnl Copyright (c) 2004-2006 The Regents of the University of California.
 dnl                         All rights reserved.
 dnl Copyright (c) 2009-2017 Cisco Systems, Inc.  All rights reserved
-dnl Copyright (c) 2008-2017 University of Houston. All rights reserved.
+dnl Copyright (c) 2008-2018 University of Houston. All rights reserved.
 dnl Copyright (c) 2015      Research Organization for Information Science
 dnl                         and Technology (RIST). All rights reserved.
 dnl $COPYRIGHT$
@@ -45,7 +45,9 @@ AC_DEFUN([OMPI_CHECK_LUSTRE],[
              [Build Lustre support, optionally adding DIR/include, DIR/lib, and DIR/lib64 to the search path for headers and libraries])])
     OPAL_CHECK_WITHDIR([lustre], [$with_lustre], [include/lustre/lustreapi.h])
 
-    AS_IF([test -z "$with_lustre" || test "$with_lustre" = "yes"],
+    AS_IF([test "$with_lustre" = "no"],
+        [ompi_check_lustre_happy="no"],
+        [AS_IF([test -z "$with_lustre" || test "$with_lustre" = "yes"],
                 [ompi_check_lustre_dir="/usr"],
                 [ompi_check_lustre_dir=$with_lustre])
             
@@ -56,8 +58,9 @@ AC_DEFUN([OMPI_CHECK_LUSTRE],[
             fi
             
             # Add correct -I and -L flags
-    OPAL_CHECK_PACKAGE([$1], [lustre/lustreapi.h], [lustreapi], [llapi_file_create], [],
-                       [$ompi_check_lustre_dir], [$ompi_check_lustre_libdir], [ompi_check_lustre_happy="yes"],
+            OPAL_CHECK_PACKAGE([$1], [lustre/lustreapi.h], [lustreapi], [llapi_file_create], 
+                [], [$ompi_check_lustre_dir], [$ompi_check_lustre_libdir], 
+                [ompi_check_lustre_happy="yes"],
                 [ompi_check_lustre_happy="no"])
             
             AC_MSG_CHECKING([for required lustre data structures])
@@ -82,7 +85,7 @@ OPAL_LOG_COMMAND(
 )
     rm -f conftest.c conftest.o
     AC_MSG_RESULT([$ompi_check_lustre_struct_happy])
-
+    ])
 
     AS_IF([test "$ompi_check_lustre_happy" = "yes"],
           [$2],