M_STATIC_ASSERT: provide expression compatible

macro even in pure C11 mode
(Remove GCC extension)

Add M_OPL_AS_STR to display the oplist conditionnaly as the generated string may be too big for some compilers.

Translate some M_STATIC_FAILURE into M_STATIC_ASSERT
as M_STATIC_FAILURE is not an expression whereas M_STATIC_ASSERT is an expression.

README.md

@@ -8562,6 +8562,9 @@ M\_USE\_DECL / M\_USE\_DEF shall be defined without effective value.
 
 See M\_USE\_DECL for more details.
 
+#### M\_USE\_PRINT\_OPLIST
+
+If defined, it displays the oplist associated to the static assert.
 
 #### M\_MEMORY\_ALLOC