Add strlcpy()/strlcat()

Refactor recurse() routine in preparation to moving tar(1) over
to use it instead of the ftw() interface.

util/strlcpy.c

@@ -0,0 +1,31 @@
+/* Taken from OpenBSD */
+#include <sys/types.h>
+#include <string.h>
+
+/*
+ * Copy src to string dst of size siz.  At most siz-1 characters
+ * will be copied.  Always NUL terminates (unless siz == 0).
+ * Returns strlen(src); if retval >= siz, truncation occurred.
+ */
+size_t
+strlcpy(char *dst, const char *src, size_t siz)
+{
+        char *d = dst;
+        const char *s = src;
+        size_t n = siz;
+        /* Copy as many bytes as will fit */
+        if (n != 0) {
+                while (--n != 0) {
+                        if ((*d++ = *s++) == '\0')
+                                break;
+                }
+        }
+        /* Not enough room in dst, add NUL and traverse rest of src */
+        if (n == 0) {
+                if (siz != 0)
+                        *d = '\0';              /* NUL-terminate dst */
+                while (*s++)
+                        ;
+        }
+        return(s - src - 1);    /* count does not include NUL */
+}