Use ATTRIBUTE_PACKED for some more enums.

After this patch, they use 1 byte instead of 4 bytes.

BUG=aomedia:940

Change-Id: Id00f2a0618e458ba7fb985ecc10d581f156a18cd

av1/common/enums.h

diff --git a/av1/common/enums.h b/av1/common/enums.h
index bbdef3f..a93d05c 100644
--- a/av1/common/enums.h
+++ b/av1/common/enums.h
@@ -304,7 +304,7 @@
   TX_TYPES_1D,
 } TX_TYPE_1D;
 
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   DCT_DCT,    // DCT  in both horizontal and vertical
   ADST_DCT,   // ADST in vertical, DCT in horizontal
   DCT_ADST,   // DCT  in vertical, ADST in horizontal

av1/common/filter.h

diff --git a/av1/common/filter.h b/av1/common/filter.h
index c955aa7..2f1689a 100644
--- a/av1/common/filter.h
+++ b/av1/common/filter.h
@@ -29,7 +29,7 @@
 #define USE_12TAP_FILTER 0
 #define USE_EXTRA_FILTER 0
 
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   EIGHTTAP_REGULAR,
   EIGHTTAP_SMOOTH,
 #if USE_EXTRA_FILTER