Use the -static switch on MinGW to prevent dependency on an external libpthread.dll on some MinGW distributions.

Source/CMake/Modules/Urho3D-CMake-magic.cmake

@@ -230,8 +230,8 @@ else ()
             endif ()
         endif ()
         if (WIN32)
-            set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -static-libgcc")
-            set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-libstdc++ -static-libgcc")
+            set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -static -static-libgcc")
+            set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static -static-libstdc++ -static-libgcc")
             # Additional compiler flags for Windows ports of GCC
             set (CMAKE_C_FLAGS_RELWITHDEBINFO "-O2 -g -DNDEBUG")
             set (CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g -DNDEBUG")