Break rtp_rtcp_format out of rtp_rtcp, to resolve circular dependencies

webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc b/webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc
index d65b11d5cf22a4d310986a7fe95bf76b4ead7615..c443f2dba3db096b1a6d182cb48a8f996564f2af 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extension_map.cc
@@ -10,8 +10,8 @@
 
 #include "webrtc/modules/rtp_rtcp/include/rtp_header_extension_map.h"
 
+#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
-#include "webrtc/modules/rtp_rtcp/source/rtp_utility.h"
 #include "webrtc/rtc_base/arraysize.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/logging.h"
@@ -19,8 +19,6 @@
 namespace webrtc {
 namespace {
 
-using RtpUtility::Word32Align;
-
 struct ExtensionInfo {
   RTPExtensionType type;
   const char* uri;