[PATCH] Revert to defining __extern_inline only for g++-4.3+

[Jakub Jelinek]

On Wed, Aug 13, 2014 at 11:53:35PM +0530, Siddhesh Poyarekar wrote:
> There is however a regression in this patch for llvm, since it reverts
> the llvm expectation that __GNUC_STDC_INLINE__ or __GNUC_GNU_INLINE__
> definition imply proper extern inline semantics.

Depends on what exactly clang does.
GCC 4.1 and 4.2 define __GNUC_GNU_INLINE__ though, and do not support
gnu_inline attribute in C++, therefore we can't let it through if
__GNUC_GNU_INLINE__ is defined, since that is not a guarantee gnu_inline
will work in C++.

	Jakub