Use Go1.11 module (#5743)

* Migrate to go modules

* make vendor

* Update mvdan.cc/xurls

* make vendor

* Update code.gitea.io/git

* make fmt-check

* Update github.com/go-sql-driver/mysql

* make vendor

vendor/github.com/golang/snappy/decode_amd64.s

@@ -2,12 +2,16 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !appengine
+// +build gc
+// +build !noasm
+
 #include "textflag.h"
 
-// func decode(dst, src []byte) int
-//
 // The asm code generally follows the pure Go code in decode_other.go, except
 // where marked with a "!!!".
+
+// func decode(dst, src []byte) int
 //
 // All local variables fit into registers. The non-zero stack size is only to
 // spill registers and push args when issuing a CALL. The register allocation:
@@ -222,6 +226,25 @@ tagLit63:
 // ----------------------------------------
 // The code below handles copy tags.
 
+tagCopy4:
+	// case tagCopy4:
+	// s += 5
+	ADDQ $5, SI
+
+	// if uint(s) > uint(len(src)) { etc }
+	MOVQ SI, BX
+	SUBQ R11, BX
+	CMPQ BX, R12
+	JA   errCorrupt
+
+	// length = 1 + int(src[s-5])>>2
+	SHRQ $2, CX
+	INCQ CX
+
+	// offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
+	MOVLQZX -4(SI), DX
+	JMP     doCopy
+
 tagCopy2:
 	// case tagCopy2:
 	// s += 3
@@ -237,7 +260,7 @@ tagCopy2:
 	SHRQ $2, CX
 	INCQ CX
 
-	// offset = int(src[s-2]) | int(src[s-1])<<8
+	// offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
 	MOVWQZX -2(SI), DX
 	JMP     doCopy
 
@@ -247,7 +270,7 @@ tagCopy:
 	//	- CX == src[s]
 	CMPQ BX, $2
 	JEQ  tagCopy2
-	JA   errUC4T
+	JA   tagCopy4
 
 	// case tagCopy1:
 	// s += 2
@@ -259,7 +282,7 @@ tagCopy:
 	CMPQ BX, R12
 	JA   errCorrupt
 
-	// offset = int(src[s-2])&0xe0<<3 | int(src[s-1])
+	// offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
 	MOVQ    CX, DX
 	ANDQ    $0xe0, DX
 	SHLQ    $3, DX
@@ -465,8 +488,3 @@ errCorrupt:
 	// return decodeErrCodeCorrupt
 	MOVQ $1, ret+48(FP)
 	RET
-
-errUC4T:
-	// return decodeErrCodeUnsupportedCopy4Tag
-	MOVQ $3, ret+48(FP)
-	RET