[RFR]: Add __tsan_symbolize_external_ex

[Arthur Eubanks]

Done.

On Wed, Mar 27, 2019 at 11:34 AM Man Cao <manc at google.com> wrote:

> Looks good.
> Minor comment is that you could add some comment on
> how __tsan_symbolize_external_ex() differs from other functions starting
> with "__tsan", and why it does not need to be inside tsanExternalDecls.hpp.
> No need for a new webrev.
>
> -Man
>
>
> On Wed, Mar 27, 2019 at 8:57 AM Arthur Eubanks <aeubanks at google.com>
> wrote:
>
>> >
>> > Any reason you want to do it two steps?
>> >
>> This slightly differs from our internal patch where we have a wrapper in
>> the launcher. I wanted to see if this difference made sense.
>>
>