Update CMake to 3.9 (#200)

Co-authored-by: Michael Graeb <[email protected]>

CMakeLists.txt

@@ -1,14 +1,10 @@
 # Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 # SPDX-License-Identifier: Apache-2.0.
 
-cmake_minimum_required(VERSION 3.0)
+cmake_minimum_required(VERSION 3.9)
 
 project(aws-c-cal LANGUAGES C VERSION 0.1.0)
 
-if (POLICY CMP0069)
-    cmake_policy(SET CMP0069 NEW) # Enable LTO/IPO if available in the compiler, see AwsCFlags
-endif()
-
 set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 
 option(BYO_CRYPTO "Set this if you want to provide your own cryptography implementation. This will cause the defaults to not be compiled." OFF)
@@ -80,7 +76,7 @@ elseif (APPLE)
            message(FATAL_ERROR "Security Framework not found")
         endif ()
 
-        
+
         find_library(COREFOUNDATION_LIB CoreFoundation)
         if(NOT COREFOUNDATION_LIB)
            message(FATAL_ERROR "CoreFoundation Framework not found")

README.md

@@ -13,7 +13,7 @@ This library is licensed under the Apache 2.0 License.
 
 ## Build Instructions
 
-CMake 3.0+ is required to build.
+CMake 3.9+ is required to build.
 
 `<install-path>` must be an absolute path in the following instructions.