Logger: Annotate logPrint with format attribute

This allows the compiler to check for mismatches in the format string and the passed parameters.

src/zm_logger.cpp

@@ -415,7 +415,7 @@ void Logger::closeSyslog() {
   (void) closelog();
 }
 
-void Logger::logPrint(bool hex, const char * const filepath, const int line, const int level, const char *fstring, ...) {
+void Logger::logPrint(bool hex, const char *filepath, int line, int level, const char *fstring, ...) {
   if (level > mEffectiveLevel) return;
   if (level < PANIC || level > DEBUG9)
     Panic("Invalid logger level %d", level);

src/zm_logger.h

@@ -174,7 +174,12 @@ private:
   void closeDatabase();
 
  public:
-  void logPrint(bool hex, const char * const filepath, const int line, const int level, const char *fstring, ...);
+  void logPrint(bool hex,
+                const char *filepath,
+                int line,
+                int level,
+                const char *fstring,
+                ...) __attribute__((format(printf, 6, 7)));
 };
 
 void logInit(const char *name, const Logger::Options &options=Logger::Options());