Rename MS_REFCNT_IS_NOT_ZERO() and MS_REFCNT_IS_ZERO() macros

[dmorissette]

As part of the work on RFC-24 the following two macros have been defined:

#define MS_REFCNT_IS_NOT_ZERO(obj) (MS_REFCNT_DECR(obj))>0
#define MS_REFCNT_IS_ZERO(obj) (MS_REFCNT_DECR(obj))<=0 

Code using those macros is confusing because it is not clear that they decrement the refcount in addition to testing whether it's zero. I proposed that we rename them to make it clear that the macros do not just test the refcount but also decrement it first. Umberto agreed with the change and we settled on the following names:

#define MS_REFCNT_DECR_IS_NOT_ZERO(obj) (MS_REFCNT_DECR(obj))>0
#define MS_REFCNT_DECR_IS_ZERO(obj) (MS_REFCNT_DECR(obj))<=0

This ticket is to track this change.

[dmorissette]

Fixed. Macros renamed in r6285