[Fwd: QUARTZ: initialize AM_MEDIA_TYPE to prevent crash]

[Alex Villací­s Lasso]

I am (still) trying to run a Japanese RPG program in Wine, and it 
requires 1) the Indeo video codecs, fortunately downloadable, and 2) 
this patch, to prevent crashing on an attempt to IUnknown_Release on a 
bogus interface.

Second attempt - first one never appeared on the mail list.

Changelog:
* Initialize mtCurrent structure to NULL to prevent calling 
IUnknown_Release on an uninitialized interface