changing CMAKE_SOURCE_DIR to CMAKE_CURRENT_SOURCE_DIR for Windows OpenCL builds
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0ff424b..f1d0aba 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -270,14 +270,14 @@
 		target_include_directories(basisu_encoder PRIVATE "OpenCL")
 
         if (BUILD_X64)
-            target_link_libraries(basisu PRIVATE "${CMAKE_SOURCE_DIR}/OpenCL/lib/OpenCL64.lib")
+            target_link_libraries(basisu PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/OpenCL/lib/OpenCL64.lib")
 			if(EXAMPLES)
-            	target_link_libraries(examples PRIVATE "${CMAKE_SOURCE_DIR}/OpenCL/lib/OpenCL64.lib")
+            	target_link_libraries(examples PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/OpenCL/lib/OpenCL64.lib")
 			endif()
         else()
-            target_link_libraries(basisu PRIVATE "${CMAKE_SOURCE_DIR}/OpenCL/lib/OpenCL.lib")
+            target_link_libraries(basisu PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/OpenCL/lib/OpenCL.lib")
 			if(EXAMPLES)
-            	target_link_libraries(examples PRIVATE "${CMAKE_SOURCE_DIR}/OpenCL/lib/OpenCL.lib")
+            	target_link_libraries(examples PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/OpenCL/lib/OpenCL.lib")
 			endif()
         endif()
     endif()