Ccache support

[Loïc Minier]

On Sun, Jan 03, 2010, Junichi Uekawa wrote:
> my preference would be to move out some parts of code to
> pbuilder-buildpackage-funcs as functions, since pbuilder-buildpackage
> is getting a bit longer and harder to read, but other than that,
> sounds good.

 Ah right, done

> I'm not sure if it would work with existing installation, would people
> end up mounting ccache directory twice if they've already set things
> up in bindmounts ?

 Well if they used the exact same dir as the new pbuilder dir, the bind
 mount will only happen once (since BINDMOUNTS is filtered through sort
 -u), but if they listed another dir, it might be that one user
 specificed BINDMOUNT dir will be bind-mounted for nothing.

 If they unset pbuilder's ccache support (CCACHEDIR), it will work just
 as before for them; if they don't, it will use the new dir.

 I added a debian/NEWS entry for the addition of ccache support; I think
 it will get the attention of people using ccache, but I could also add
 another warning if CCACHE_DIR is set and we're about to override it.
 e.g. "Warning: overriding user-set CCACHE_DIR" (or we could decide not
 to override it, but IMO it's best for the long term if pbuilder manages
 that entirely).

-- 
Loïc Minier