util: Replace raw struct functions with stdplus

These functions were recently added to stdplus as they are useful across
projects.

Change-Id: Ia383715a253fce71dacc6bc72b1771393e8ed600
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/configure.ac b/configure.ac
index ee783e2..1dc2bf0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -32,6 +32,7 @@
 PKG_CHECK_MODULES([SYSTEMD], [libsystemd >= 221])
 PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus])
 PKG_CHECK_MODULES([SDEVENTPLUS], [sdeventplus])
+PKG_CHECK_MODULES([STDPLUS], [stdplus])
 AC_PATH_PROG([SDBUSPLUSPLUS], [sdbus++])
 PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging])
 PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces])