libtins: force C++17 for gtest

pkgs/by-name/li/libtins/0001-force-cpp-14.patch pkgs/by-name/li/libtins/0001-force-cpp-17.patch

···
-This change bypasses all the code that attempts to see which C++11 features are enabled in your specific C++11 compiler.  C++14 is required for gtest 1.13+.
+This change bypasses all the code that attempts to see which C++11 features are enabled in your specific C++11 compiler.  C++17 is required for gtest 1.17+.
 diff --git a/CMakeLists.txt b/CMakeLists.txt
 index 902233e676ee..49ac8a1010a4 100644
 --- a/CMakeLists.txt
···
 -    ENDIF()
 +    SET(TINS_HAVE_CXX11 ON)
 +    MESSAGE(STATUS "Using C++11 features")
-+    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
++    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17")
  ELSE(LIBTINS_ENABLE_CXX11)
      MESSAGE(
          WARNING

pkgs/by-name/li/libtins/package.nix

···
   };
 
   patches = [
-    # Required for gtest 1.13+, see also upstream report at:
-    # https://github.com/mfontanini/libtins/issues/529
-    ./0001-force-cpp-14.patch
+    # Required for gtest 1.17+:
+    # https://github.com/NixOS/nixpkgs/issues/425358
+    # See also an upstream report for gtest 1.13+ and C++14:
+    # https://github.com/mfontanini/libtins/issues/
+    ./0001-force-cpp-17.patch
   ];
 
   postPatch = ''