eliminate macro redefine error when used in biicode

include/nana/config.hpp

@@ -23,7 +23,6 @@
 	#if defined(__MINGW32__)
 		#define NANA_MINGW
 		#define STD_CODECVT_NOT_SUPPORTED
-		//#define STD_THREAD_NOT_SUPPORTED	//Use this flag if MinGW version is older than 4.8.1
 	#endif
 #elif (defined(linux) || defined(__linux) || defined(__linux__) || defined(__GNU__) || defined(__GLIBC__)) && !defined(_CRAYC)
 //Linux:
@@ -31,13 +30,29 @@
 	#define NANA_X11	1
 	#define PLATFORM_SPEC_HPP <nana/detail/linux_X11/platform_spec.hpp>
 	#define STD_CODECVT_NOT_SUPPORTED
+#else
+#   error   "Only Windows and Unix are support now"
+#endif
+
+// C++11 detection
+#if defined(__GNUC_MINOR__)
+#   if __GNUC_MINOR__ < 8
+#       define NANA_NO_CPP11
+#   endif
+#elif _MSC_VER < 1700
+#   define NANA_NO_CPP11
+#endif
+
+#if defined(NANA_NO_CPP11)
+#   define STD_THREAD_NOT_SUPPORTED
 #endif
 
 //Here defines some flags that tell Nana what features will be supported.
 
-#define NANA_UNICODE
+#define NANA_ENABLE_PNG
+#define NANA_UNICODE    // always use unicode, don't make users confusing!
 
-#if defined(NANA_UNICODE) && defined(NANA_WINDOWS)
+#if defined(NANA_WINDOWS)
 	#ifndef _UNICODE
 		#define _UNICODE
 	#endif
@@ -47,13 +62,4 @@
 	#endif
 #endif
 
-//Support for PNG
-//	Comment it to disable the feature of support for PNG.
-//#define NANA_ENABLE_PNG
-#if defined(NANA_ENABLE_PNG)
-	//Comment it to use libpng from operating system.
-	#define NANA_LIBPNG
-#endif
-
-
 #endif	//NANA_CONFIG_HPP

include/nana/deploy.hpp

@@ -24,7 +24,7 @@
 #endif
 
 //Implement workarounds for MinGW
-#if defined(NANA_MINGW) && __GNUC_MINOR__ < 8
+#if NANA_NO_CPP11
 namespace std
 {
 	//Workaround for no implemenation of std::stoi in MinGW.

include/nana/std_condition_variable.hpp

@@ -2,7 +2,7 @@
 #define NANA_STD_CONDITION_VARIABLE_HPP
 #include <nana/config.hpp>
 
-#if defined(STD_THREAD_NOT_SUPPORTED) && !defined(NANA_MINGW) || __GNUC_MINOR__ < 8
+#if NANA_NO_CPP11
 
 #include <boost/thread/condition_variable.hpp>
 namespace std

include/nana/std_mutex.hpp

@@ -2,7 +2,7 @@
 #define NANA_STD_MUTEX_HPP
 #include <nana/config.hpp>
 
-#if defined(STD_THREAD_NOT_SUPPORTED) && !defined(NANA_MINGW) || __GNUC_MINOR__ < 8
+#if NANA_NO_CPP11
 
 #include <boost/thread/mutex.hpp>
 #include <boost/thread/recursive_mutex.hpp>

include/nana/std_thread.hpp

@@ -2,7 +2,7 @@
 #define NANA_STD_THREAD_HPP
 #include <nana/config.hpp>
 
-#if defined(STD_THREAD_NOT_SUPPORTED) && !defined(NANA_MINGW) || __GNUC_MINOR__ < 8
+#if NANA_NO_CPP11
 #include <boost/thread.hpp>
 namespace std
 {