build: put the Win64 SDL libraries in two separate directories, MSVC-built

and MinGW-built, because of some weird %rip corruption at runtime when
linking the MSVC DLL with mingw-w64.

build/vs2010/Lol.Core.Vars.props

@@ -14,7 +14,7 @@
     <SdlMixerDir>$(ContribDir)\sdl-mixer-1.2.11</SdlMixerDir>
     <SdlIncludes>$(SdlDir)\include;$(SdlImageDir)\include;$(SdlMixerDir)\include</SdlIncludes>
     <SdlLibs Condition="'$(Platform)'=='Win32'">$(SdlDir)\lib\i686-w64-mingw32;$(SdlImageDir)\lib\i686-w64-mingw32;$(SdlMixerDir)\lib\i686-w64-mingw32</SdlLibs>
-    <SdlLibs Condition="'$(Platform)'=='x64'">$(SdlDir)\lib\x86_64-w64-mingw32</SdlLibs>
+    <SdlLibs Condition="'$(Platform)'=='x64'">$(SdlDir)\lib\x86_64-msvc</SdlLibs>
     <SdlDeps Condition="'$(Platform)'=='Win32'">SDL.lib;SDLmain.lib;SDL_image.lib;SDL_mixer.lib</SdlDeps>
     <SdlDeps Condition="'$(Platform)'=='x64'">SDL.lib;SDLmain.lib</SdlDeps>
     <Win32Defines>HAVE_SDL_H;USE_SDL;$(Win32Defines)</Win32Defines>