Bug fixes in pattern_formatter and async_logger

example/Makefile

 CXX	= g++
-CXX_FLAGS = -Wall -Wshadow -Wextra -pedantic -std=c++11 -pthread -I../include
+CXX_FLAGS = -Wall -Wextra -pedantic -std=c++11 -pthread -I../include
 CXX_RELEASE_FLAGS = -O3 -march=native
 CXX_DEBUG_FLAGS= -g
 

include/spdlog/details/async_logger_impl.h

@@ -39,7 +39,7 @@ inline spdlog::async_logger::async_logger(
 inline void spdlog::async_logger::sink_it_(details::log_msg &msg)
 {
 #if defined(SPDLOG_ENABLE_MESSAGE_COUNTER)
-    _incr_msg_counter(msg);
+    incr_msg_counter_(msg);
 #endif
     if (auto pool_ptr = thread_pool_.lock())
     {