BUG: Fix copy/paste error in previous commit that references wrong variable

(wxWidgets_INCLUDE_DIRS instead of wxWidgets_DEFINITIONS).

Modules/FindwxWidgets.cmake

@@ -708,7 +708,7 @@ ELSE(wxWidgets_FIND_STYLE STREQUAL "win32")
         STRING(REGEX REPLACE "-D[^;]+;" ""
           wxWidgets_CXX_FLAGS "${wxWidgets_CXX_FLAGS}")
         STRING(REPLACE "-D" ""
-          wxWidgets_INCLUDE_DIRS "${wxWidgets_DEFINITIONS}")
+          wxWidgets_DEFINITIONS "${wxWidgets_DEFINITIONS}")
 
         # parse include dirs from cxxflags; drop -I prefix
         STRING(REGEX MATCHALL "-I[^;]+"