Add function to give a different seed for randoms

src/clocks.c

@@ -30,6 +30,7 @@
 
 /* Standard headers. */
 #include <stdio.h>
+#include <limits.h>
 #include <unistd.h>
 
 /* Local headers. */
@@ -280,3 +281,23 @@ double clocks_get_cputime_used(void) {
   times(&tmstic);
   return (double)(tmstic.tms_utime + tmstic.tms_cutime);
 }
+
+/**
+ * @brief Return an integer based on the current time.
+ *
+ * Normally this will be the remainder of the current number of nanoseconds
+ * so not very dissimilar in the most significant figures unless the time
+ * between calls is greater than INT_MAX nanoseconds. For faster calls use
+ * fewer figures, if that matters.
+ *
+ * @result an integer.
+ */
+int clocks_random_seed(void) {
+    struct timespec timespec;
+#ifdef HAVE_CLOCK_GETTIME
+    clock_gettime(CLOCK_REALTIME, &timespec);
+    return (timespec.tv_nsec % INT_MAX);
+#else
+    return (getticks() % INT_MAX);
+#endif
+}

src/clocks.h

@@ -44,5 +44,6 @@ double clocks_diff_ticks(ticks tic, ticks toc);
 const char *clocks_get_timesincestart(void);
 
 double clocks_get_cputime_used(void);
+int clocks_random_seed(void);
 
 #endif /* SWIFT_CLOCKS_H */