Bug 1421635 - av1: Disable decoding on 32-bit x86. r=kinetik

Work around crashes on win32 by disabling the decoder for
that target and 32-bit linux. Machines limited to 32 bits
are likely too slow for effective software playback anyway.

MozReview-Commit-ID: FP4wxP3FPOQ

--HG--
extra : rebase_source : 9bdd8a3719c21bb1d26af8272894cf7be46a02f4

toolkit/moz.configure

@@ -375,7 +375,7 @@ option('--enable-av1',
 def av1(value, target, milestone):
     enabled = bool(value)
     if value.origin == 'default' and milestone.is_nightly:
-        enabled = target.os != 'Android'
+        enabled = target.os != 'Android' and target.cpu != 'x86'
     if enabled:
         return True