Update CMake to 3.9 (#458)

Co-authored-by: Michael Graeb <graebm@amazon.com>

Author: waahm7

CMakeLists.txt

@@ -1,11 +1,7 @@
 
-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.9)
 project(aws-c-s3 C)
 
-if (POLICY CMP0069)
-    cmake_policy(SET CMP0069 NEW) # Enable LTO/IPO if available in the compiler, see AwsCFlags
-endif()
-
 option(ASSERT_LOCK_HELD "Enable ASSERT_SYNCED_DATA_LOCK_HELD for checking thread issue" OFF)
 option(ENABLE_MOCK_SERVER_TESTS "Whether to run the integration tests that rely on pre-configured mock server" OFF)
 option(ENABLE_MRAP_TESTS "Whether to run the integration tests that rely on pre-configured multi-region access point" OFF)

README.md

@@ -23,7 +23,7 @@ This library is licensed under the Apache 2.0 License.
 
 ### Building
 
-CMake 3.1+ is required to build.
+CMake 3.9+ is required to build.
 
 `<install-path>` must be an absolute path in the following instructions.