Expand --no-touch-headers to include the private header.

Expand --no-touch-headers to include the private header.

It seems incredibly bizarre that --no-touch-headers does not impact
generation of the private header file.  Even though this behaviour
is documented in the man page, I'm going to go out on a limb and
posit that nobody using this option wants or relies on the current
behaviour.  So let's just change it to make sense.