Implement -Dbuiltin_cling=Off

Cling needs to be built and installed as part of llvm/clang and
then we need to specify paths as we do for builtin_clang=Off.

CMakeLists.txt

@@ -330,6 +330,8 @@ macro(set_cling_windows_version_resource_properties name)
   endif()
 endmacro()
 
+include_directories(BEFORE ${LLVM_INCLUDE_DIRS} ${CLANG_INCLUDE_DIRS})
+
 macro(add_cling_library name)
   cmake_parse_arguments(ARG
     "SHARED"
@@ -447,28 +449,6 @@ endmacro(add_cling_executable)
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
-option(ROOT_CLASSIC "Building as part of the ROOT (classic)." OFF)
-
-if(DEFINED ROOT_BINARY_DIR)
-  # Building as part of ROOT (CMake)
-  include_directories(BEFORE
-    ${CMAKE_BINARY_DIR}/interpreter/llvm/src/tools/clang/include
-    ${CMAKE_SOURCE_DIR}/interpreter/llvm/src/tools/clang/include
-    )
-elseif(ROOT_CLASSIC)
-  # Building as part of ROOT (classic)
-  include_directories(BEFORE
-    ${CMAKE_CURRENT_BINARY_DIR}/../llvm/obj/tools/clang/include
-    ${CMAKE_CURRENT_SOURCE_DIR}/../llvm/src/tools/clang/include
-    )
-else()
-  # and this when building Cling standalone:
-  include_directories(BEFORE
-    ${CMAKE_CURRENT_BINARY_DIR}/../clang/include
-    ${CMAKE_CURRENT_SOURCE_DIR}/../clang/include
-    )
-endif()
-
 include_directories(BEFORE
   ${CMAKE_CURRENT_BINARY_DIR}/include
   ${CMAKE_CURRENT_SOURCE_DIR}/include

lib/Interpreter/CMakeLists.txt

@@ -6,7 +6,8 @@
 # LICENSE.TXT for details.
 #------------------------------------------------------------------------------
 
-set(CLING_DEPEND_LIBS
+set(LIBS
+  clingUtils
   clangCodeGen
   clangDriver
   clangFrontend
@@ -20,11 +21,6 @@ set(CLING_DEPEND_LIBS
   clangAST
   clangBasic
   clangLex
-  CACHE STRING "Dependency Clang libraries for Cling"
-)
-
-set(LIBS
-  clingUtils
 )
 
 set(LLVM_LINK_COMPONENTS
@@ -103,7 +99,6 @@ add_cling_library(clingInterpreter OBJECT
   ${CLING_DEPENDS}
 
   LINK_LIBS
-  ${CLING_DEPEND_LIBS}
   ${LIBS}
   ${CMAKE_DL_LIBS}
   )