vendor: initial vendor

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/docker/cli/opts/envfile.go

@@ -0,0 +1,22 @@
+package opts
+
+import (
+	"os"
+)
+
+// ParseEnvFile reads a file with environment variables enumerated by lines
+//
+// ``Environment variable names used by the utilities in the Shell and
+// Utilities volume of IEEE Std 1003.1-2001 consist solely of uppercase
+// letters, digits, and the '_' (underscore) from the characters defined in
+// Portable Character Set and do not begin with a digit. *But*, other
+// characters may be permitted by an implementation; applications shall
+// tolerate the presence of such names.''
+// -- http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
+//
+// As of #16585, it's up to application inside docker to validate or not
+// environment variables, that's why we just strip leading whitespace and
+// nothing more.
+func ParseEnvFile(filename string) ([]string, error) {
+	return parseKeyValueFile(filename, os.LookupEnv)
+}