Revert "Modern Cross-Platform CMake C++11 requirement"

This reverts commit c9914a2.

This is why we can't have nice things.

CMakeLists.txt

@@ -16,7 +16,7 @@
 # along with this program; if not, see <http://www.gnu.org/licenses/>.
 #============================================================================
 
-cmake_minimum_required(VERSION 3.1.0)
+cmake_minimum_required(VERSION 2.8.9)
 
 # For checks in subdirectories
 set(InOpenJK TRUE)
@@ -231,8 +231,7 @@ elseif (("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU") OR ("${CMAKE_C_COMPILER_ID}" S
 	set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
 
 	# enable somewhat modern C++
-	set(CMAKE_CXX_STANDARD 11)
-	set(CMAKE_CXX_STANDARD_REQUIRED ON)
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 
 	if("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")
 		set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")