win64: remove console

win64/Toolchain-mingw64.cmake

@@ -65,3 +65,8 @@ set (Boost_LIB_VERSION   "1_56")
 set (Boost_MAJOR_VERSION  "1")
 set (Boost_MINOR_VERSION   "56")
 set (Boost_SUBMINOR_VERSION "0")
+
+# remove console
+set(CMAKE_EXE_LINKER_FLAGS
+    "${CMAKE_EXE_LINKER_FLAGS} -Wl,--subsystem,windows"
+)