1. __STDC_VERSION__ isn't necessarily defined (e.g., by C++
compilers). So check to make sure it is defined before we actually
check the value.
2. If we're in C++11 (or later), use static_assert().
3. Split the static assert macro in two macros:
* THIS_SYMBOL_WAS_REMOVED_IN_MPI30(...): Insert a valid expression
(i.e., 0, because it's only used with MPI_Datatype values, and
since MPI_Datatype is a pointer, 0 is a valid RHS expression)
before invoking the static assert so that we don't get a syntax
error instead of the actual static assert error.
* THIS_FUNCTION_WAS_REMOVED_IN_MPI30(...): No need for the valid
expression; just invoke the assert functionality.
Also remove an errant "\".
Thanks to Constantine Khrulev and Martin Audet for identifying the
issue and suggesting to use C11's static_assert().
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
(cherry picked from commit 835f8f1834b8798a23ee0db6ad94315e30cb9be3)