[PATCH] Fix up definitions for older G++

[Marek Polacek]

On Sun, Sep 09, 2012 at 01:24:57AM +0400, Dmitry V. Levin wrote:
> Wouldn't a disjunctive form be easier to read?  E.g.
> #if (!defined __cplusplus && defined __GNUC__) || __GNUC_PREREQ (4,3)

Dunno.  I can make that change if others agree.

	Marek