Move a typedef to aom_codec.h from aom_encoder.h

BUG=aomedia:2535

Change-Id: Id5dc9b61cf303bdcf2ea56da84c07e51e23bc254
diff --git a/aom/aom_codec.h b/aom/aom_codec.h
index 6773e07..ce034b3 100644
--- a/aom/aom_codec.h
+++ b/aom/aom_codec.h
@@ -173,6 +173,13 @@
  */
 typedef long aom_codec_flags_t;
 
+/*!\brief Time Stamp Type
+ *
+ * An integer, which when multiplied by the stream's time base, provides
+ * the absolute time of a sample.
+ */
+typedef int64_t aom_codec_pts_t;
+
 /*!\brief Codec interface structure.
  *
  * Contains function pointers and other data private to the codec
diff --git a/aom/aom_encoder.h b/aom/aom_encoder.h
index cad8d0f..39203c0 100644
--- a/aom/aom_encoder.h
+++ b/aom/aom_encoder.h
@@ -78,13 +78,6 @@
   size_t sz;       /**< Length of the buffer, in chars */
 } aom_fixed_buf_t; /**< alias for struct aom_fixed_buf */
 
-/*!\brief Time Stamp Type
- *
- * An integer, which when multiplied by the stream's time base, provides
- * the absolute time of a sample.
- */
-typedef int64_t aom_codec_pts_t;
-
 /*!\brief Compressed Frame Flags
  *
  * This type represents a bitfield containing information about a compressed
diff --git a/common/ivfdec.h b/common/ivfdec.h
index 9d81919..dbc7733 100644
--- a/common/ivfdec.h
+++ b/common/ivfdec.h
@@ -11,7 +11,7 @@
 #ifndef AOM_COMMON_IVFDEC_H_
 #define AOM_COMMON_IVFDEC_H_
 
-#include "aom/aom_encoder.h"
+#include "aom/aom_codec.h"
 #include "common/tools_common.h"
 
 #ifdef __cplusplus