Link test to librt if it contains clock_gettime(2).
This resolves #257.
diff --git a/configure.ac b/configure.ac
index 2308b99..7a1290e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1190,6 +1190,14 @@
CPPFLAGS="$CPPFLAGS -D_REENTRANT"
+dnl Check whether clock_gettime(2) is in libc or librt. This function is only
+dnl used in test code, so save the result to TESTLIBS to avoid poluting LIBS.
+SAVED_LIBS="${LIBS}"
+LIBS=
+AC_SEARCH_LIBS([clock_gettime], [rt], [TESTLIBS="${LIBS}"])
+AC_SUBST([TESTLIBS])
+LIBS="${SAVED_LIBS}"
+
dnl Check if the GNU-specific secure_getenv function exists.
AC_CHECK_FUNC([secure_getenv],
[have_secure_getenv="1"],
@@ -1694,6 +1702,7 @@
AC_MSG_RESULT([LDFLAGS : ${LDFLAGS}])
AC_MSG_RESULT([EXTRA_LDFLAGS : ${EXTRA_LDFLAGS}])
AC_MSG_RESULT([LIBS : ${LIBS}])
+AC_MSG_RESULT([TESTLIBS : ${TESTLIBS}])
AC_MSG_RESULT([RPATH_EXTRA : ${RPATH_EXTRA}])
AC_MSG_RESULT([])
AC_MSG_RESULT([XSLTPROC : ${XSLTPROC}])