Support vmodule filter support on non GNU compilers

[garyturnbull]

Currently the vmodule implementation is limited to GNU compilers as it uses a compiler specific extension for the VLOG_IS_ON() macro. This can be written using an inline lambda in Visual Studio 2015 and likely any compiler with C++11 support. It may also make sense to replace the current GNU specific implementation with a common one based on a lambda if the compiler supports it.

Here's an implementation that works with Visual Studio 2015 from vlog_is_on.h.

#define VLOG_IS_ON(verboselevel)	\
[]()	\
{	\
    static google::int32* vlocal__ = &google::kLogSiteUninitialized;	\
    google::int32 verbose_level__ = (verboselevel);	\
    return (*vlocal__ >= verbose_level__) &&	\
        ((vlocal__ != &google::kLogSiteUninitialized) ||	\
        (google::InitVLOG3__(&vlocal__, &FLAGS_v,	\
            __FILE__, verbose_level__))); 	\
}()