Search for llvm-symbolizer binary in the same directory as argv[0], before
looking for it along $PATH. This allows installs of LLVM tools outside of
$PATH to find the symbolizer and produce pretty backtraces if they crash.

llvm-svn: 272232
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 467392e..6891204 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -327,7 +327,7 @@
 // main for opt
 //
 int main(int argc, char **argv) {
-  sys::PrintStackTraceOnErrorSignal();
+  sys::PrintStackTraceOnErrorSignal(argv[0]);
   llvm::PrettyStackTraceProgram X(argc, argv);
 
   // Enable debug stream buffering.