Move MetadataHeader to libui

To remove BufferHubMetadata off pdx dependency.

Note that the __attribute__(packed) is removed as part of this CL, as
it's not really needed and is triggering clang warnings.

Test: build passed. Not test needed as no behavior changes.
Bug: 118893702
Change-Id: Ifae94a143a2bedef68a653c57f089b95d166e6d7
diff --git a/libs/ui/BufferHubBuffer.cpp b/libs/ui/BufferHubBuffer.cpp
index 3816c1b..36eaed9 100644
--- a/libs/ui/BufferHubBuffer.cpp
+++ b/libs/ui/BufferHubBuffer.cpp
@@ -40,6 +40,7 @@
 
 #include <android-base/unique_fd.h>
 #include <ui/BufferHubBuffer.h>
+#include <ui/BufferHubDefs.h>
 
 using android::base::unique_fd;
 using android::dvr::BufferTraits;
@@ -69,7 +70,6 @@
 using dvr::BufferHubDefs::IsClientPosted;
 using dvr::BufferHubDefs::IsClientReleased;
 using dvr::BufferHubDefs::kHighBitsMask;
-using dvr::BufferHubDefs::kMetadataHeaderSize;
 
 } // namespace
 
@@ -161,7 +161,7 @@
     }
 
     size_t metadataSize = static_cast<size_t>(bufferTraits.metadata_size());
-    if (metadataSize < kMetadataHeaderSize) {
+    if (metadataSize < BufferHubDefs::kMetadataHeaderSize) {
         ALOGE("BufferHubBuffer::ImportGraphicBuffer: metadata too small: %zu", metadataSize);
         return -EINVAL;
     }