add -std=c++14 to CXXFLAGS

to fix incompatibility of error handling with C++17 Standard

pkgs/development/libraries/ucommon/default.nix

@@ -20,6 +20,9 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ pkg-config ];
 
+  # use C++14 Standard until error handling code gets updated upstream
+  CXXFLAGS = [ "-std=c++14" ];
+
   # disable flaky networking test
   postPatch = ''
     substituteInPlace test/stream.cpp \