vendor: check vendor directory (go-delve#1962)

Remove gitignore rule preventing vendor/modules.txt file from being
commited, add check that the vendor directory is synchronized.

.gitignore

@@ -1,4 +1,3 @@
-**/*.txt
 **/*.test
 .tags*
 tags

scripts/make.go

@@ -193,9 +193,11 @@ func getoutput(cmd string, args ...interface{}) string {
 	x.Env = os.Environ()
 	out, err := x.Output()
 	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error executing %s %v\n", cmd, args)
 		log.Fatal(err)
 	}
 	if !x.ProcessState.Success() {
+		fmt.Fprintf(os.Stderr, "Error executing %s %v\n", cmd, args)
 		os.Exit(1)
 	}
 	return string(out)
@@ -416,7 +418,7 @@ func inpath(exe string) bool {
 
 func allPackages() []string {
 	r := []string{}
-	for _, dir := range strings.Split(getoutput("go", "list", "./..."), "\n") {
+	for _, dir := range strings.Split(getoutput("go", "list", "-mod=vendor", "./..."), "\n") {
 		dir = strings.TrimSpace(dir)
 		if dir == "" || strings.Contains(dir, "/vendor/") || strings.Contains(dir, "/scripts") {
 			continue
@@ -428,5 +430,6 @@ func allPackages() []string {
 }
 
 func main() {
+	allPackages() // checks that vendor directory is synced as a side effect
 	NewMakeCommands().Execute()
 }

vendor/modules.txt

@@ -0,0 +1,47 @@
+# github.com/cosiner/argv v0.0.0-20170225145430-13bacc38a0a5
+github.com/cosiner/argv
+# github.com/google/go-dap v0.2.0
+github.com/google/go-dap
+# github.com/hashicorp/golang-lru v0.5.4
+github.com/hashicorp/golang-lru/simplelru
+# github.com/inconshreveable/mousetrap v1.0.0
+github.com/inconshreveable/mousetrap
+# github.com/mattn/go-colorable v0.0.0-20170327083344-ded68f7a9561
+github.com/mattn/go-colorable
+# github.com/mattn/go-isatty v0.0.3
+github.com/mattn/go-isatty
+# github.com/peterh/liner v0.0.0-20170317030525-88609521dc4b
+github.com/peterh/liner
+# github.com/pkg/profile v0.0.0-20170413231811-06b906832ed0
+github.com/pkg/profile
+# github.com/sirupsen/logrus v0.0.0-20180523074243-ea8897e79973
+github.com/sirupsen/logrus
+# github.com/spf13/cobra v0.0.0-20170417170307-b6cb39589372
+github.com/spf13/cobra
+# github.com/spf13/pflag v0.0.0-20170417173400-9e4c21054fa1
+github.com/spf13/pflag
+# go.starlark.net v0.0.0-20190702223751-32f345186213
+go.starlark.net/internal/compile
+go.starlark.net/internal/spell
+go.starlark.net/resolve
+go.starlark.net/starlark
+go.starlark.net/syntax
+# golang.org/x/arch v0.0.0-20190927153633-4e8777c89be4
+golang.org/x/arch/arm64/arm64asm
+golang.org/x/arch/x86/x86asm
+# golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2
+golang.org/x/crypto/ssh/terminal
+# golang.org/x/sys v0.0.0-20190626221950-04f50cda93cb
+golang.org/x/sys/unix
+golang.org/x/sys/windows
+# golang.org/x/tools v0.0.0-20191127201027-ecd32218bd7f
+golang.org/x/tools/go/gcexportdata
+golang.org/x/tools/go/internal/gcimporter
+golang.org/x/tools/go/internal/packagesdriver
+golang.org/x/tools/go/packages
+golang.org/x/tools/internal/fastwalk
+golang.org/x/tools/internal/gopathwalk
+golang.org/x/tools/internal/semver
+golang.org/x/tools/internal/span
+# gopkg.in/yaml.v2 v2.2.1
+gopkg.in/yaml.v2