Don't use gnu extensions which are too new for debian and ubuntu

src/modules/keyboard_state.cpp

@@ -24,13 +24,6 @@ class errno_error : public std::runtime_error {
     std::string error_msg{msg};
     error_msg += ": ";
 
-#ifdef _GNU_SOURCE
-    // strerrorname_np gets the error code's name; it's nice to have, but it's a GNU extension
-    const auto errno_name = strerrorname_np(err);
-    error_msg += errno_name;
-    error_msg += " ";
-#endif
-
     // strerror(3) man page says 1024 should be a big enough buffer to avoid ERANGE
     char errno_str[1024] = {};
     strerror_r(err, errno_str, sizeof errno_str);