Remove mallocarray(...) and use reallocarray(NULL, ...)

After a short correspondence with Otto Moerbeek it turned out
mallocarray() is only in the OpenBSD-Kernel, because the kernel-
malloc doesn't have realloc.
Userspace applications should rather use reallocarray with an
explicit NULL-pointer.

Assuming reallocarray() will become available in c-stdlibs in the
next few years, we nip mallocarray() in the bud to allow an easy
transition to a system-provided version when the day comes.

strings.c

@@ -15,7 +15,7 @@ strings(FILE *fp, const char *fname, size_t len)
 	size_t i, bread;
 	off_t off;
 
-	rbuf = emallocarray(len, sizeof(*rbuf));
+	rbuf = ereallocarray(NULL, len, sizeof(*rbuf));
 
 	for (off = 0, i = 0; (bread = efgetrune(&r, fp, fname)); ) {
 		off += bread;