Update CMake to 3.9 (#47)

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

CMakeLists.txt

@@ -1,13 +1,9 @@
 # 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-sdkutils 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()
-
 if (DEFINED CMAKE_PREFIX_PATH)
     file(TO_CMAKE_PATH "${CMAKE_PREFIX_PATH}" CMAKE_PREFIX_PATH)
 endif()

README.md

@@ -11,7 +11,7 @@ This library is licensed under the Apache 2.0 License.
 
 ### Building
 
-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.
 
@@ -26,4 +26,4 @@ cmake --build aws-c-common/build --target install
 git clone [email protected]:awslabs/aws-c-sdkutils.git
 cmake -S aws-c-sdkutils -B aws-c-sdkutils/build -DCMAKE_INSTALL_PREFIX=<install-path> -DCMAKE_PREFIX_PATH=<install-path>
 cmake --build aws-c-sdkutils/build --target install
-```
+```