RFR: 8149591 - Prepare hotspot for GTest

[Kim Barrett]

> On Feb 10, 2016, at 8:01 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> Why not replace
> 
>  report_assert_msg(err_msg(__VA_ARGS__).buffer())
> 
> with
> 
>  report_assert_msg(__VA_ARGS__)
> 
> Unless report_assert_msg is not provided by us, but is instead part of
> the gtest framework.  In that case, we provide a variadic wrapper
> around report_assert_msg and call that wrapper in the vmassert
> expansion.

And remember to give the variadic function the appropriate ATTRIBUTE_PRINTF.