* need to include iostream as well as stdio.h when doing the tricks with

MPI::SEEK_* because iostreams (well, ios_base, but I don't think that
    should be included directly) can use SEEK_* as values in an enum, which
    means that 'const int' is bad for them.
  * Remove now useless comments in the cxx example programs
  * include iostream after mpi.h so that our examples work with other MPI
    implementations that don't try to be as friendly with the constants.

Refs trac:387

This commit was SVN r12125.

The following Trac tickets were found above:
  Ticket 387 --> https://svn.open-mpi.org/trac/ompi/ticket/387

examples/hello_cxx.cc

@@ -7,15 +7,8 @@
 // Sample MPI "hello world" application in C++
 //
 
-// MPI's C++ bindings unfortunately redefined some POSIX constants
-// (SEEK_SET and friends).  Fortunately, most versions of <iostream>
-// and <stdio.h> are sane enough that if you include "mpi.h" first,
-// they won't redefine the problematic values.  Note, however, that
-// this means that you should not make calls to fseek(3) (and friends)
-// in a C++ source file that includes <mpi.h>!
-
-#include <iostream>
 #include "mpi.h"
+#include <iostream>
 
 int main(int argc, char **argv)
 {

examples/ring_cxx.cc

@@ -7,15 +7,8 @@
 // Simple ring test program
 //
 
-// MPI's C++ bindings unfortunately redefined some POSIX constants
-// (SEEK_SET and friends).  Fortunately, most versions of <iostream>
-// and <stdio.h> are sane enough that if you include "mpi.h" first,
-// they won't redefine the problematic values.  Note, however, that
-// this means that you should not make calls to fseek(3) (and friends)
-// in a C++ source file that includes <mpi.h>!
-
-#include <iostream>
 #include "mpi.h"
+#include <iostream>
 
 int main(int argc, char *argv[])
 {

ompi/mpi/cxx/mpicxx.h

@@ -37,8 +37,16 @@
 #include <stdarg.h>
 
 #if !defined(OMPI_IGNORE_CXX_SEEK) & OMPI_WANT_MPI_CXX_SEEK
+// We need to include the header files that define SEEK_* or use them
+// in ways that require them to be #defines so that if the user
+// includes them later, the double inclusion logic in the headers will
+// prevent trouble from occuring.
+
 // include so that we can smash SEEK_* properly
 #include <stdio.h>
+// include because on Linux, there is one place that assumes SEEK_* is
+// a #define (it's used in an enum).
+#include <iostream>
 
 // smash SEEK_* #defines
 #ifdef SEEK_SET