Fixed header include problems.

include/spdlog/details/logger_impl.h

@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include "./line_logger.h"
+#include <spdlog/logger.h>
 
 // create logger with given name, sinks and the default pattern formatter
 // all other ctors will call this one
@@ -296,4 +296,4 @@ inline void spdlog::logger::flush()
 {
     for (auto& sink : _sinks)
         sink->flush();
-}
+}