CFT: fix OfflineIMAP lockup in single-threaded mode

[Eygene Ryabinkin]

Wed, Jan 30, 2013 at 10:30:53AM +0400, Eygene Ryabinkin wrote:
> Though OK, seems like this variant is a no-go, because there are too
> much cons and objections raised, so I'll craft the other one, that
> will most likely use global 'options' and fully-constifying approach
> for that: anything that needs read-only access to the 'options' will
> have it through the global object and if someone needs write access,
> then the real 'options' should be passed there.

Here we go, the variant with module-global variable that holds the
read-only copy of 'options'.  The latter is synchronized with the
real 'options', so modifications of the real options are visible
to the consumers of read-only instance.

Patch:
  http://codelabs.ru/patches/offlineimap/2013-altpatch-create-global-options-instance.diff

And the modified patch for suggestthreads():
  http://codelabs.ru/patches/offlineimap/2013-altpatch-IMAP-dont-suggest-multithreading-in-singlethreaded-mode.diff
-- 
rea