Update CCLANG_OCL_HEADERS_DIR to use default opencl_headers

Change-Id: Ifc6d89b832b9e2ecdcef687c91f1de22786fa13d

Author: iwwu

IGC/BiFModule/CMakeLists.txt

@@ -173,7 +173,7 @@ endif()
       if(EXISTS ${CCLANG_SRC})
         set(IGC_CCLANG_HOME_DIR ${CCLANG_SRC})
 		message(STATUS "Setup common clang source path from buildplan argument")
-      endif(NOT EXISTS ${IGC_CCLANG_HOME_DIR})
+      endif(EXISTS ${CCLANG_SRC})
     endif(NOT IGC_CCLANG_HOME_DIR)
     get_filename_component(IGC_CCLANG_HOME_DIR "${IGC_CCLANG_HOME_DIR}" ABSOLUTE)
     # Set build directory
@@ -182,9 +182,13 @@ endif()
       set(CCLANG_INSTALL_ARTIFACTS_DIR ${IGC_TARGET__TOOLS_CLANG_DIR})
       message(STATUS "Trigger common clang compilation from ${IGC_CCLANG_HOME_DIR} to ${CCLANG_INSTALL_ARTIFACTS_DIR}")
 
-      if(NOT OCL_HEADERS_DIR)
-        get_filename_component(OCL_HEADERS_DIR "${IGC_BUILD__GFX_DEV_SRC_DIR}/third_party/opencl_headers" ABSOLUTE)
-      endif()
+      if(NOT CCLANG_OCL_HEADERS_DIR)
+        if (EXISTS "${IGC_BUILD__GFX_DEV_SRC_DIR}/third_party/opencl_headers")
+          set(CCLANG_OCL_HEADERS_DIR "${IGC_BUILD__GFX_DEV_SRC_DIR}/third_party/opencl_headers")
+        else()
+          get_filename_component(CCLANG_OCL_HEADERS_DIR "${IGC_BUILD__GFX_DEV_SRC_DIR}/../opencl_headers" ABSOLUTE)
+        endif()
+      endif(NOT CCLANG_OCL_HEADERS_DIR)
       add_subdirectory(${IGC_CCLANG_HOME_DIR} ${IGC_CCLANG_BUILD_DIR})
       add_dependencies(GetClang "${CCLANG_LIB_NAME}")