Use pc_from_ucontext.m4 from Google Performance Tools

This M4 module lets us learn the right way (out of at least 18
possibilities) to extract the current PC for stack-trace-fixup-in-signal
purposes.  The Google Performance Tools license is 3-clause BSD.

1 files changed, 33 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
index 4ed3bd8da..8a6fccaf4 100644
--- a/LICENSE
+++ b/LICENSE
@@ -135,6 +135,39 @@ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 DATABASE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ===============================================================================
+m4/pc_from_ucontext.m4 is available under the following license.  Note that
+it is *not* built into the Tor license.
+
+Copyright (c) 2005, Google Inc.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+    * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+===============================================================================
 If you got Tor as a static binary with OpenSSL included, then you should know:
  "This product includes software developed by the OpenSSL Project
  for use in the OpenSSL Toolkit (http://www.openssl.org/)"