entropy: Port to OpenBSD

OpenBSD's entropy design is superior to Linux.

README

@@ -61,4 +61,3 @@ Porting to OpenBSD is the current goal before thinking about a release.
 
 The following functions are not portable at the moment:
 - wifi_{perc,essid}
-- entropy

components/entropy.c

@@ -14,5 +14,9 @@
 		       bprintf("%d", num) : NULL;
 	}
 #elif defined(__OpenBSD__)
-	/* unimplemented */
+	const char *
+	entropy(void)
+	{
+		return "∞";
+	}
 #endif