go.mod: require go-delve/liner instead of peterh/liner (#2905)

Use of `replace` in go.mod breaks delve installation using
`go install`. (see https://github.com/golang/go/issues/40276)
Workaround this limitation by explicitly require the fork
github.com/go-delve/liner.

go-delve/liner@v1.2.2-1 already has go.mod module name fixed
to be github.com/go-delve/liner.

Fixes go-delve/delve#2904

vendor/github.com/go-delve/liner/unixmode.go

@@ -0,0 +1,37 @@
+//go:build linux || darwin || freebsd || openbsd || netbsd
+// +build linux darwin freebsd openbsd netbsd
+
+package liner
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func (mode *termios) ApplyMode() error {
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(syscall.Stdin), setTermios, uintptr(unsafe.Pointer(mode)))
+
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+// TerminalMode returns the current terminal input mode as an InputModeSetter.
+//
+// This function is provided for convenience, and should
+// not be necessary for most users of liner.
+func TerminalMode() (ModeApplier, error) {
+	return getMode(syscall.Stdin)
+}
+
+func getMode(handle int) (*termios, error) {
+	var mode termios
+	var err error
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(handle), getTermios, uintptr(unsafe.Pointer(&mode)))
+	if errno != 0 {
+		err = errno
+	}
+
+	return &mode, err
+}