Require CMake 3.5 or newer. The recent versions of CMake started to warn about compatibility with older CMake versions than 3.5.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index cab797e..2613063 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
-cmake_minimum_required(VERSION 3.4)
+cmake_minimum_required(VERSION 3.5)
project(MD4C C)
set(MD_VERSION_MAJOR 0)