testlibraw: build the CLOCK_MONOTONIC_RAW test conditionally

CLOCK_MONOTONIC_RAW is a somewhat recent addition, and some older
toolchains/kernels may not have the support for it. Therefore, we
build the part of the test that uses CLOCK_MONOTONIC_RAW only when
this definition is available.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/tools/testlibraw.c b/tools/testlibraw.c
index d8a0702..ae37157 100644
--- a/tools/testlibraw.c
+++ b/tools/testlibraw.c
@@ -211,6 +211,7 @@
 	printf("    local time from CLOCK_MONOTONIC: %lld us\n",
 	       (unsigned long long)local_time);
 	retval = raw1394_read_cycle_timer_and_clock(handle, &ct, &local_time,
 	if (retval < 0) {
@@ -221,6 +222,7 @@
 	       ct >> 25, (ct >> 12) & 0x1fff, ct & 0xfff);
 	printf("    local time from CLOCK_MONOTONIC_RAW: %lld us\n",
 	       (unsigned long long)local_time);
 int test_card(int card)