Add packaging and release automation

vendor/github.com/muesli/termenv/termenv_posix.go

@@ -0,0 +1,17 @@
+//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || zos
+// +build darwin dragonfly freebsd linux netbsd openbsd zos
+
+package termenv
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+func isForeground(fd int) bool {
+	pgrp, err := unix.IoctlGetInt(fd, unix.TIOCGPGRP)
+	if err != nil {
+		return false
+	}
+
+	return pgrp == unix.Getpgrp()
+}