cmake: bump minimum required version to 3.3

Adapt our `target_link_libraries` call based on the version of LLVM
to account for policy `CMP0023` NEW behavior.

Author: bradking

CMakeLists.txt

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #=============================================================================
-cmake_minimum_required(VERSION 2.8.5)
+cmake_minimum_required(VERSION 3.3)
 project(CastXML)
 
 include(src/Version.cmake)

src/CMakeLists.txt

@@ -66,7 +66,12 @@ if(LLVM_LINK_LLVM_DYLIB)
   set(USE_SHARED USE_SHARED)
 endif()
 llvm_config(castxml ${USE_SHARED} ${llvm_libs})
-target_link_libraries(castxml PRIVATE ${clang_libs})
+if(LLVM_VERSION_MAJOR GREATER 5)
+  set(maybe_PRIVATE "PRIVATE")
+else()
+  set(maybe_PRIVATE "")
+endif()
+target_link_libraries(castxml ${maybe_PRIVATE} ${clang_libs})
 
 set_property(SOURCE Utils.cxx APPEND PROPERTY COMPILE_DEFINITIONS
   "CASTXML_INSTALL_DATA_DIR=\"${CastXML_INSTALL_DATA_DIR}\"")

test/run.cmake

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #=============================================================================
-cmake_minimum_required(VERSION 2.8.5)
+cmake_minimum_required(VERSION 3.3)
 
 if(xml)
   file(REMOVE "${xml}")