Makefile: Revise utsname and clock_gettime test

Clean up the feature target by outsourcing the test to an own variable.
Change the print output and don't write to the build-details file.
HAS_CLOCK_GETTIME=no replaces DISABLE_CLOCK_GETTIME=yes

This is in preparation for further changes.

Change-Id: Ie1f43b3d5a8ad79bff3f9bbc21f359ec35abc42a
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/58618
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72253
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Makefile.d/utsname_test.c b/Makefile.d/utsname_test.c
new file mode 100644
index 0000000..7bc6665
--- /dev/null
+++ b/Makefile.d/utsname_test.c
@@ -0,0 +1,9 @@
+#include <sys/utsname.h>
+struct utsname osinfo;
+int main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+	uname(&osinfo);
+	return 0;
+}