llvm-cxxfilt: fix program description

Fix a silly copy-paste error in the tool description.  Take the
opportunity to add crash stack printing which will hopefully never be
needed.

llvm-svn: 292579
diff --git a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
index 525cea2..16dd37f 100644
--- a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
+++ b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
@@ -36,7 +36,10 @@
 }
 
 int main(int argc, char **argv) {
-  cl::ParseCommandLineOptions(argc, argv, "llvm symbol table dumper\n");
+  sys::PrintStackTraceOnErrorSignal(argv[0]);
+  PrettyStackTraceProgram X(argc, argv);
+
+  cl::ParseCommandLineOptions(argc, argv, "llvm symbol undecoration tool\n");
 
   if (Decorated.empty())
     for (std::string Mangled; std::getline(std::cin, Mangled);)