build: use c++17

Update CMakeLists to use c++17.

Change-Id: I968465fa76fe032fb49af1cde7b9932505988659
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 52780ba..0aa5bb4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 2.8.10 FATAL_ERROR)
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/gpio/inc)