Merge pull request libgit2#4375 from mhagger/cmake-version-3.0.x

Fix compilation for CMake versions 3.0.x where x >= 1

Author: pks-t

CMakeLists.txt

@@ -14,7 +14,7 @@
 PROJECT(libgit2 C)
 CMAKE_MINIMUM_REQUIRED(VERSION 2.8.11)
 CMAKE_POLICY(SET CMP0015 NEW)
-IF (CMAKE_VERSION VERSION_GREATER 3.0)
+IF (NOT CMAKE_VERSION VERSION_LESS 3.1)
 	CMAKE_POLICY(SET CMP0051 NEW)
 ENDIF()