Escape '{' and '}' in command line args in Windows
Escape '{' and '}' in command line args in Windows

(Windows-only)

Escape '{' and '}' with backslashes in command line arguments.  Without
this change, curly braces mysteriously disappear from commands passed to
`exec.Command`.

apache/incubator-mynewt-newt,apache/incubator-mynewt-newt