Remove various bits of lint.

Change-Id: I5f8f61766d2add7fd7ff40d463ea03cb20515988
diff --git a/src/signal_catcher.h b/src/signal_catcher.h
index 89132c9..8554531 100644
--- a/src/signal_catcher.h
+++ b/src/signal_catcher.h
@@ -31,7 +31,7 @@
  */
 class SignalCatcher {
  public:
-  SignalCatcher(const std::string& stack_trace_file);
+  explicit SignalCatcher(const std::string& stack_trace_file);
   ~SignalCatcher();
 
   void HandleSigQuit();