fuzz: change return values to 1 rather than 0 or -1

This allows gofuzz to store the mutating input as coverage if it reaches
any new coverage, even if it didn't make it to the end of the test.

fuzz/brontide/random_init_encrypt.go

@@ -12,7 +12,7 @@ import (
 func Fuzz_random_init_encrypt(data []byte) int {
 	// Ensure that length of message is not greater than max allowed size.
 	if len(data) > math.MaxUint16 {
-		return 0
+		return 1
 	}
 
 	// This will return brontide machines with random keys.