moved MSVC strdup define to libssh2_config.h which we include already.

example/ssh2.c

@@ -32,11 +32,6 @@
 #include <arpa/inet.h>
 #endif
 
-#if defined(_WIN32) && !defined(__GNUC__)
-/* plain MSVC setups have no normal strdup */
-#define strdup _strdup
-#endif
-
 #include <sys/types.h>
 #include <fcntl.h>
 #include <errno.h>

win32/libssh2_config.h

@@ -26,6 +26,7 @@
 #if _MSC_VER < 1500
 #define vsnprintf _vsnprintf
 #endif
+#define strdup _strdup
 #define strncasecmp _strnicmp
 #define strcasecmp _stricmp
 #else