Removed PkgConfig check for gtk version since we don't use 2 anywhere

CMakeLists.txt

@@ -447,22 +447,8 @@ else()
         PROPERTIES COMPILE_FLAGS "-ObjC++")
     ENDIF(VTK_USE_COCOA)
   else()
-    find_package(PkgConfig)
-    if("-lwx_gtk2u_core-3.0" IN_LIST wxWidgets_LIBRARIES)
-      pkg_check_modules(GTK2 REQUIRED gtk+-2.0)
-      include_directories(${GTK2_INCLUDE_DIRS})
-      link_libraries(${GTK2_LIBRARIES})
-    elseif("-lwx_gtk3u_core-3.0" IN_LIST wxWidgets_LIBRARIES)
-      pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
-      include_directories(${GTK3_INCLUDE_DIRS})
-      link_libraries(${GTK3_LIBRARIES})
-    elseif("-lwx_gtk3u_core-3.2" IN_LIST wxWidgets_LIBRARIES)
-      pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
-      include_directories(${GTK3_INCLUDE_DIRS})
-      link_libraries(${GTK3_LIBRARIES})
-    else()
-      message(FATAL_ERROR "Didn't find -lwx_gtk2u_core-3.0 or -lwx_gtk3u_core-3.0 in wxWidgets_LIBRARIES - unable to detect GTK version to use: ${wxWidgets_LIBRARIES}")
-    endif()
+    include_directories(${GTK3_INCLUDE_DIRS})
+    link_libraries(${GTK3_LIBRARIES})
   endif()
 endif()