Force CMake 3.4.3 like llvm.

interpreter/cling/CMakeLists.txt

-cmake_minimum_required(VERSION 2.8.8)
-
-# FIXME: It may be removed when we use 2.8.12.
-if(CMAKE_VERSION VERSION_LESS 2.8.12)
-  # Invalidate a couple of keywords.
-  set(cmake_2_8_12_INTERFACE)
-  set(cmake_2_8_12_PRIVATE)
-else()
-  # Use ${cmake_2_8_12_KEYWORD} intead of KEYWORD in target_link_libraries().
-  set(cmake_2_8_12_INTERFACE INTERFACE)
-  set(cmake_2_8_12_PRIVATE PRIVATE)
-  if(POLICY CMP0022)
-    cmake_policy(SET CMP0022 NEW) # automatic when 2.8.12 is required
-  endif()
-endif()
+cmake_minimum_required(VERSION 3.4.3)
 
 # If we are not building as a part of LLVM, build Cling as an
 # standalone project, using LLVM as an external library:
@@ -290,7 +276,7 @@ macro(add_cling_library name)
   llvm_add_library(${name} ${ARG_ENABLE_SHARED} ${ARG_UNPARSED_ARGUMENTS} ${srcs})
 
   if(TARGET ${name})
-    target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${LLVM_COMMON_LIBS})
+    target_link_libraries(${name} ${INTERFACE} ${LLVM_COMMON_LIBS})
 
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "libcling")
       install(TARGETS ${name}