Require cmake >= 3.1.2 (for correct openssl 1.0.2 detection)

@ygj6 reported:
  "My platform is MacOS 10.13.5, This problem only happens on Mac.

   As written in the file CMakeLists.txt, the minimum required version of cmake is 3.1:
     cmake_minimum_required(VERSION 3.1 FATAL_ERROR)
   So I built this project with cmake-3.1.0, but I got the following errors:

       CMake Error at /usr/local/cmake-3.1.0/share/cmake/Modules/FindOpenSSL.cmake:293 (list):
         list GET given empty list
       Call Stack (most recent call first):
         CMakeLists.txt:824 (find_package)

       CMake Error at /usr/local/cmake-3.1.0/share/cmake/Modules/FindOpenSSL.cmake:294 (list):
         list GET given empty list
       Call Stack (most recent call first):
         CMakeLists.txt:824 (find_package)

       CMake Error at /usr/local/cmake-3.1.0/share/cmake/Modules/FindOpenSSL.cmake:296 (list):
         list GET given empty list
       Call Stack (most recent call first):
         CMakeLists.txt:824 (find_package)

       CMake Error at /usr/local/cmake-3.1.0/share/cmake/Modules/FindOpenSSL.cmake:298 (list):
         list GET given empty list
       Call Stack (most recent call first):
         CMakeLists.txt:824 (find_package)

   I googled this error and got this answer:
     https://bugs.archlinux.org/task/43688

   It is a bug in FindOpenSSL.cmake on cmake-3.1.0 and fixed on cmake-3.1.2 .
   Of course, It was successful when rebuilding with cmake-3.1.2 .
   So I suggest setting the minimum version required for cmake to 3.1.2 or higher.
   "

Closes: #845
Refs: https://github.com/Kitware/CMake/commit/de4ccee75a89519f95fcbcca75abc46577bfefea

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e2089f832a4b4e94fb94159bbb69e225baeebac3..5aca8a924717ab23263ebc2697cd4416f7b8bc52 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,7 +19,7 @@
 #       start libevent.sln
 #
 
-cmake_minimum_required(VERSION 3.1 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.1.2 FATAL_ERROR)
 
 if (POLICY CMP0054)
     cmake_policy(SET CMP0054 NEW)