configure.ac: check clock_gettime for glib < 2.17
glib < 2.17 doesn't support clock_gettime directly, it is available
via librt.
Change-Id: Ice853d85ffe859b1d4df48b91b050c24d85c861b
diff --git a/configure.ac b/configure.ac
index bc3358a..4a00e69 100644
--- a/configure.ac
+++ b/configure.ac
@@ -68,6 +68,10 @@
AC_CHECK_LIB(execinfo, backtrace, BACKTRACE_LIB=-lexecinfo, BACKTRACE_LIB=)
AC_SUBST(BACKTRACE_LIB)
+# check for old glibc < 2.17 to get clock_gettime
+AC_SEARCH_LIBS([clock_gettime], [rt posix4], [LIBRARY_RT="$LIBS";LIBS=""])
+AC_SUBST(LIBRARY_RT)
+
AC_ARG_ENABLE(doxygen,
[AS_HELP_STRING(
[--disable-doxygen],
diff --git a/src/Makefile.am b/src/Makefile.am
index e9db32f..dca5865 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -12,7 +12,7 @@
lib_LTLIBRARIES = libosmocore.la
-libosmocore_la_LIBADD = $(BACKTRACE_LIB) $(TALLOC_LIBS)
+libosmocore_la_LIBADD = $(BACKTRACE_LIB) $(TALLOC_LIBS) $(LIBRARY_RT)
libosmocore_la_SOURCES = timer.c timer_gettimeofday.c timer_clockgettime.c \
select.c signal.c msgb.c bits.c \
bitvec.c bitcomp.c counter.c fsm.c \