abseil-cpp requires at least C++14

Index: ext/libclementine-tagreader/CMakeLists.txt
--- ext/libclementine-tagreader/CMakeLists.txt.orig
+++ ext/libclementine-tagreader/CMakeLists.txt
@@ -3,7 +3,7 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 include_directories(${CMAKE_SOURCE_DIR}/ext/libclementine-common)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --std=c++0x")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --std=c++17")
 
 set(MESSAGES
   tagreadermessages.proto
