x/ref: Remove flag support from cmdline.

We originally added flag support to handle overriding the default
value of the flag when generating godoc.  E.g. we wanted
${HOME}/foo to show up in godoc, but /usr/home/toddw/foo to show
up regularly.

The new mechanism is to perform lookups on the FlagSet and
override the DefValue directly, which is a simpler mechanism.

MultiPart: 3/3
Change-Id: I7e54832f2f41d7f91e6b7604a6120d79f7c464ab
4 files changed