ToolManager: move #include <wx/eventfilter.h> to cpp file

This fixes a link error with MSVC and sccache:

wxbase31u.lib(wxbase315u_vc_custom.dll) : error LNK2005: "public: __cdecl wxEventFilter::wxEventFilter(void)" (??0wxEventFilter@@QEAA@XZ) already defined in ToolManager.cpp.obj
wxbase31u.lib(wxbase315u_vc_custom.dll) : error LNK2005: "public: virtual __cdecl wxEventFilter::~wxEventFilter(void)" (??1wxEventFilter@@UEAA@XZ) already defined in ToolManager.cpp.obj

Signed-off-by: Be <be@mixxx.org>

src/toolbars/ToolManager.cpp

@@ -49,6 +49,7 @@
 #include <wx/window.h>
 #endif  /*  */
 
+#include <wx/eventfilter.h> // to inherit
 #include <wx/minifram.h>
 #include <wx/popupwin.h>
 

src/toolbars/ToolManager.h

@@ -16,7 +16,6 @@
 #include <functional>
 
 #include <wx/defs.h>
-#include <wx/eventfilter.h> // to inherit
 #include <wx/frame.h> // to inherit
 #include <wx/timer.h> // member variable