Check for clock_gettime, and add -lrt to BENCH_LIBS if needed.

Rev: nettle/configure.ac:1.25

configure.ac

@@ -522,6 +522,19 @@ fi
 
 AC_SUBST(OPENSSL_LIBFLAGS)
 
+# clock_gettime is in librt on *-*-osf5.1 and on glibc, so add -lrt to
+# BENCH_LIBS if needed. On linux (tested on x86_32, 2.6.26),
+# clock_getres reports ns accuracy, while in a quick test on osf
+# clock_getres said only 1 millisecond.
+
+old_LIBS="$LIBS"
+AC_SEARCH_LIBS(clock_gettime, rt, [
+  AC_DEFINE([HAVE_CLOCK_GETTIME],1,[Define to 1 if you have the `clock_gettime' function])])
+BENCH_LIBS="$LIBS"
+LIBS="$old_LIBS"
+
+AC_SUBST(BENCH_LIBS)
+
 # Set these flags *last*, or else the test programs won't compile
 if test x$GCC = xyes ; then
   # Using -ggdb3 makes (some versions of) Redhat's gcc-2.96 dump core