Test for time.h constants

tests/Makefile

@@ -77,6 +77,7 @@ EXPECT_NAMES=\
 	strings \
 	sys_mman \
 	time/asctime \
+	time/constants \
 	time/gmtime \
 	time/localtime \
 	time/macros \

tests/expected/time/constants.stdout

@@ -0,0 +1,2 @@
+(nil)
+1000000

tests/time/constants.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <time.h>
+
+int main(void) {
+    /* TODO: ensure that it is really time.h supplying the NULL constant */
+    printf("%p\n", NULL);
+
+    /* Cast to long to avoid format string mismatch in case CLOCKS_PER_SEC is
+    defined as some other type. The expected value (1 million) will always fit
+    in a long and will always have that value on conforming systems. */
+    printf("%ld\n", (long)CLOCKS_PER_SEC);
+}