hg: tsan/dev: Add __tsan_symbolize_external_ex()

[aeubanks at google.com]

Changeset: 28f0415a0822
Author:    aeubanks
Date:      2019-03-27 11:40 -0700
URL:       http://hg.openjdk.java.net/tsan/dev/rev/28f0415a0822

Add __tsan_symbolize_external_ex()

This is the function that TSAN calls to symbolize a stack frame produced by Java.
The actual implementation will come later.

! src/hotspot/share/runtime/tsan.cpp