crypto/sha3: Remove import path checking from vendored code

crypto/sha3/doc.go

@@ -63,4 +63,4 @@
 // They produce output of the same length, with the same security strengths
 // against all attacks. This means, in particular, that SHA3-256 only has
 // 128-bit collision resistance, because its output length is 32 bytes.
-package sha3 // import "golang.org/x/crypto/sha3"
+package sha3