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/llvm-cov/llvm-cov.cpp b/llvm/tools/llvm-cov/llvm-cov.cpp
index 8c5acae..ba60cd9 100644
--- a/llvm/tools/llvm-cov/llvm-cov.cpp
+++ b/llvm/tools/llvm-cov/llvm-cov.cpp
@@ -14,8 +14,11 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Process.h"
+#include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
 #include <string>
 
@@ -51,6 +54,11 @@
 }
 
 int main(int argc, const char **argv) {
+  // Print a stack trace if we signal out.
+  sys::PrintStackTraceOnErrorSignal(argv[0]);
+  PrettyStackTraceProgram X(argc, argv);
+  llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
+
   // If argv[0] is or ends with 'gcov', always be gcov compatible
   if (sys::path::stem(argv[0]).endswith_lower("gcov"))
     return gcovMain(argc, argv);