CORBA24 — #pragma rules are too restrictive

I think the current rules for #pragma are too tight and we need to relax
them. In particular, for the ID pragma (page 10-43):

If an attempt is made to assign a repository ID to the same
IDL construct a second time, a compile-time diagnostic shall
be emitted, regardless of whether the second ID is in conflict or not:

interface A {};
#pragma ID A "IDL:A:1.1"
#pragma ID A "IDL:X:1.1" // Compile-time error

interface B {};
#pragma ID B "IDL:BB:1.1"
#pragma ID B "IDL:BB:1.1" // Compile-time error

This causes problems with separate compilation. For example:

// x.idl
namespace Foo

;
#pragma ID Foo "IDL:blah:1.0"

// z.idl
#include "x.idl"
#include "y.idl"

The same problem arises with the version pragma, because I may want to
change the version in two different source files.

Clarify as suggested