configury: enhance the check for ISO_FORTRAN_ENV module

When real*16 is supported, test with real128 kind.
Test with real32 kind otherwise.

Thanks Alan Wild for reporting this issue.

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

config/ompi_fortran_check_iso_fortran_env.m4

@@ -11,6 +11,8 @@ dnl                         University of Stuttgart.  All rights reserved.
 dnl Copyright (c) 2004-2005 The Regents of the University of California.
 dnl                         All rights reserved.
 dnl Copyright (c) 2010-2014 Cisco Systems, Inc.  All rights reserved.
+dnl Copyright (c) 2020      Research Organization for Information Science
+dnl                         and Technology (RIST). All rights reserved.
 dnl $COPYRIGHT$
 dnl
 dnl Additional copyrights may follow
@@ -24,12 +26,16 @@ dnl
 # ----------------------------------------------------
 AC_DEFUN([OMPI_FORTRAN_CHECK_ISO_FORTRAN_ENV],[
     AS_VAR_PUSHDEF([iso_fortran_env_var], [ompi_cv_fortran_have_iso_fortran_env])
+    OPAL_VAR_SCOPE_PUSH([iso_fortran_env_kind])
 
     AC_CACHE_CHECK([if Fortran compiler supports ISO_FORTRAN_ENV], iso_fortran_env_var,
-       [AC_LANG_PUSH([Fortran])
+       [AS_IF([test $OMPI_HAVE_FORTRAN_REAL16 -eq 1],
+              [iso_fortran_env_kind=real128],
+              [iso_fortran_env_kind=real32])
+        AC_LANG_PUSH([Fortran])
         AC_COMPILE_IFELSE([AC_LANG_SOURCE([[program check_for_iso_fortran_env
    use, intrinsic :: iso_fortran_env
-   real(real32) :: var
+   real($iso_fortran_env_kind) :: var
    var = 12.34
 end program]])],
              [AS_VAR_SET(iso_fortran_env_var, yes)],
@@ -37,6 +43,7 @@ end program]])],
         AC_LANG_POP([Fortran])
        ])
 
+    OPAL_VAR_SCOPE_POP
     AS_VAR_IF(iso_fortran_env_var, [yes], [$1], [$2])
     AS_VAR_POPDEF([iso_fortran_env_var])
 ])