Correct apparent typo in fix for bug 693

Patch 323d535 fixes the reported bug but doesn't correctly read a
global transformation of type TRANSLATION or AFFINE. Fortunately,
clang gives a warning about the ignored expression.

Change-Id: I1127d5d5b809bf016872a3ba97903599869d5357
diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index dc6c959..89c1718 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -4757,7 +4757,7 @@
     if (aom_read_bit(r, ACCT_STR))
       type = ROTZOOM;
     else
-      aom_read_bit(r, ACCT_STR) ? TRANSLATION : AFFINE;
+      type = aom_read_bit(r, ACCT_STR) ? TRANSLATION : AFFINE;
 #endif  // GLOBAL_TRANS_TYPES > 4
   }