Do not escape ${libdir} in --with-pkgconfigdir option's AS_HELP_STRING

description parameter (not needed and ends up in output).
Signed-off-by: Stefan Knoblich <s.knoblich@axsentis.de>

configure.in

@@ -94,7 +94,7 @@ AC_SUBST(bindir)
 AC_SUBST(includedir)
 
 AC_ARG_WITH([pkgconfigdir],
-	[AS_HELP_STRING([--with-pkgconfigdir=DIR], [Installation directory for pkgconfig file (default: \${libdir}/pkgconfig)])],
+	[AS_HELP_STRING([--with-pkgconfigdir=DIR], [Installation directory for pkgconfig file (default: ${libdir}/pkgconfig)])],
 	[case "${withval}" in
 	 yes|no) AC_MSG_ERROR([Invalid value ${withval} for option --with-pkgconfigdir]) ;;
 	 *) pkgconfigdir="${withval}" ;;