configury: remove now obsolete reference to OPAL_PTRDIFF_TYPE

since Open MPI now requires a C99, and ptrdiff_t type is part of C99,
there is no more need for the abstract OPAL_PTRDIFF_TYPE type.

Thanks George, Nathan and Paul for the help.

Author: ggouaillardet

config/ompi_find_mpi_aint_count_offset.m4

@@ -15,7 +15,7 @@
 # Copyright (c) 2006-2007 Los Alamos National Security, LLC.  All rights
 #                         reserved.
 # Copyright (c) 2009      Oak Ridge National Labs.  All rights reserved.
-# Copyright (c) 2014      Research Organization for Information Science
+# Copyright (c) 2014-2016 Research Organization for Information Science
 #                         and Technology (RIST). All rights reserved.
 # Copyright (c) 2015      Intel, Inc. All rights reserved.
 # $COPYRIGHT$
@@ -42,14 +42,13 @@ AC_DEFUN([OMPI_FIND_MPI_AINT_COUNT_OFFSET],[
 dnl #########################################################################
 
 AC_DEFUN([_OMPI_FIND_MPI_AINT_TYPE], [
-    # Find the type of MPI_Aint.  We already did the work to figure
-    # out what opal_ptrdiff will be; just use that.
+    # MPI_Aint type is ptrdiff_t; just use that.
     AC_MSG_CHECKING([for type of MPI_Aint])
 
-    MPI_AINT_TYPE=$opal_ptrdiff_t
+    MPI_AINT_TYPE=ptrdiff_t
     # Get the size of this type; we'll need it to figure out Fortran's
     # MPI_ADDRESS_KIND, later
-    MPI_AINT_SIZE=$opal_ptrdiff_size
+    MPI_AINT_SIZE=$ac_cv_sizeof_ptrdiff_t
     AC_DEFINE_UNQUOTED(OMPI_MPI_AINT_TYPE, [$MPI_AINT_TYPE],
                        [Type of MPI_Aint])
 

configure.ac

@@ -408,6 +408,8 @@ if test "$ac_cv_type_ssize_t" = yes ; then
 fi
 if test "$ac_cv_type_ptrdiff_t" = yes; then
     AC_CHECK_SIZEOF(ptrdiff_t)
+else
+    AC_MSG_ERROR([ptrdiff_t type is not available, this is required by C99 standard.  Cannot continue])
 fi
 AC_CHECK_SIZEOF(wchar_t)
 
@@ -770,27 +772,6 @@ AC_INCLUDES_DEFAULT
 #endif
 ])
 
-#
-# Check for ptrdiff type.  Yes, there are platforms where
-# sizeof(void*) != sizeof(long) (64 bit Windows, apparently).
-#
-AC_MSG_CHECKING([for pointer diff type])
-if test $ac_cv_type_ptrdiff_t = yes ; then
-    opal_ptrdiff_t="ptrdiff_t"
-    opal_ptrdiff_size=$ac_cv_sizeof_ptrdiff_t
-elif test $ac_cv_sizeof_void_p -eq $ac_cv_sizeof_long ; then
-    opal_ptrdiff_t="long"
-    opal_ptrdiff_size=$ac_cv_sizeof_long
-elif test $ac_cv_type_long_long = yes && test $ac_cv_sizeof_void_p -eq $ac_cv_sizeof_long_long ; then
-    opal_ptrdiff_t="long long"
-    opal_ptrdiff_size=$ac_cv_sizeof_long_long
-else
-    AC_MSG_ERROR([Could not find datatype to emulate ptrdiff_t.  Cannot continue])
-fi
-AC_DEFINE_UNQUOTED([OPAL_PTRDIFF_TYPE], [$opal_ptrdiff_t],
-    [type to use for ptrdiff_t])
-AC_MSG_RESULT([$opal_ptrdiff_t (size: $opal_ptrdiff_size)])
-
 #
 # Find corresponding types for MPI_Aint, MPI_Count, and MPI_Offset.
 # And if relevant, find the corresponding MPI_ADDRESS_KIND,