cmake: Require cmake 2.8.5

I've improved FindOpenSSL and FindZLIB in that version to work well with
Windows and Linux. This was 2011 it should be old enough that most
distributions have at least this version available.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

CMakeLists.txt

@@ -1,7 +1,7 @@
 project(libssh C)
 
 # Required cmake version
-cmake_minimum_required(VERSION 2.8.0)
+cmake_minimum_required(VERSION 2.8.5)
 
 # global needed variables
 set(APPLICATION_NAME ${PROJECT_NAME})