Fix uninitialized loop variable

puer.c

@@ -169,7 +169,7 @@ void feed_hash(struct hashstate *state, unsigned char input[], size_t length) {
 	// Invariant: The buffer will be filled somewhere between 0 and 15
 	// when we enter this loop. This is because once it reaches 16, the
 	// hash compression function is executed.
-	for (size_t i; i < length; i++) {
+	for (size_t i = 0; i < length; i++) {
 		// Must not overflow the internat counter. In practice we will not
 		// hit this.
 		assert(state->totalbits <= UINT64_MAX - 8);