Add ATTRIBUTE_PACKED to some enum types.

Add ATTRIBUTE_PACKED to all the enum types used in the MB_MODE_INFO
structure. This is a futile attempt to make the 'mip' array in
AV1_COMMON (cm->mip) smaller.

Also add ATTRIBUTE_PACKED to the other enum types defined in the
modified header files, except for BITSTREAM_PROFILE.

BUG=oss-fuzz:9497

Change-Id: I41b4b9da39fcd8e41410e363b55425dff51c8661

av1/common/blockd.h

diff --git a/av1/common/blockd.h b/av1/common/blockd.h
index 979f13b..da65cfe 100644
--- a/av1/common/blockd.h
+++ b/av1/common/blockd.h
@@ -38,13 +38,13 @@
 #define MAX_DIFFWTD_MASK_BITS 1
 
 // DIFFWTD_MASK_TYPES should not surpass 1 << MAX_DIFFWTD_MASK_BITS
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   DIFFWTD_38 = 0,
   DIFFWTD_38_INV,
   DIFFWTD_MASK_TYPES,
 } DIFFWTD_MASK_TYPE;
 
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   KEY_FRAME = 0,
   INTER_FRAME = 1,
   INTRA_ONLY_FRAME = 2,  // replaces intra-only
@@ -376,7 +376,7 @@
 }
 #endif
 
-enum mv_precision { MV_PRECISION_Q3, MV_PRECISION_Q4 };
+enum ATTRIBUTE_PACKED mv_precision { MV_PRECISION_Q3, MV_PRECISION_Q4 };
 
 struct buf_2d {
   uint8_t *buf;

av1/common/enums.h

diff --git a/av1/common/enums.h b/av1/common/enums.h
index 689c25f..bd4dcc8 100644
--- a/av1/common/enums.h
+++ b/av1/common/enums.h
@@ -274,7 +274,7 @@
   TX_TYPES,
 } TX_TYPE;
 
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   REG_REG,
   REG_SMOOTH,
   REG_SHARP,
@@ -478,7 +478,7 @@
   INTERINTRA_MODES
 } INTERINTRA_MODE;
 
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   COMPOUND_AVERAGE,
   COMPOUND_WEDGE,
   COMPOUND_DIFFWTD,

av1/common/mv.h

diff --git a/av1/common/mv.h b/av1/common/mv.h
index c249564..2f2e7f2 100644
--- a/av1/common/mv.h
+++ b/av1/common/mv.h
@@ -56,7 +56,7 @@
 #define WARPEDDIFF_PREC_BITS (WARPEDMODEL_PREC_BITS - WARPEDPIXEL_PREC_BITS)
 
 /* clang-format off */
-typedef enum {
+typedef enum ATTRIBUTE_PACKED {
   IDENTITY = 0,      // identity transformation, 0-parameter
   TRANSLATION = 1,   // translational motion 2-parameter
   ROTZOOM = 2,       // simplified affine with rotation + zoom only, 4-parameter