crypto: fix megacheck warnings (#14917)

* crypto: fix megacheck warnings

* crypto/ecies: remove ASN.1 support

crypto/sha3/sha3.go

@@ -42,9 +42,8 @@ type state struct {
 	storage [maxRate]byte
 
 	// Specific to SHA-3 and SHAKE.
-	fixedOutput bool            // whether this is a fixed-output-length instance
-	outputLen   int             // the default output size in bytes
-	state       spongeDirection // whether the sponge is absorbing or squeezing
+	outputLen int             // the default output size in bytes
+	state     spongeDirection // whether the sponge is absorbing or squeezing
 }
 
 // BlockSize returns the rate of sponge underlying this hash function.