util: Remove temporary strings in getIgnoredInterfaces

Change-Id: I75be67b88a3f7b4dff6de9af25d3f496be09da14
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/util.hpp b/util.hpp
index 9c180ee..804d492 100644
--- a/util.hpp
+++ b/util.hpp
@@ -169,13 +169,13 @@
 void executeCommandinChildProcess(const char* path, char** args);
 
 /** @brief Get ignored interfaces from environment */
-std::string getIgnoredInterfacesEnv();
+std::string_view getIgnoredInterfacesEnv();
 
 /** @brief Parse the comma separated interface names */
-std::set<std::string> parseInterfaces(const std::string& interfaces);
+std::set<std::string_view> parseInterfaces(std::string_view interfaces);
 
 /** @brief Get the ignored interfaces */
-const std::set<std::string>& getIgnoredInterfaces();
+const std::set<std::string_view>& getIgnoredInterfaces();
 
 } // namespace internal