Comment out unused parameter.

* Prepare for -Werror.

Test: normal build.
Change-Id: I066d8bce6b4fd2a6b6e94b026adc2d84dd6c10dd
diff --git a/libs/vr/libdvr/dvr_buffer_queue.cpp b/libs/vr/libdvr/dvr_buffer_queue.cpp
index 035252d..a4c9536 100644
--- a/libs/vr/libdvr/dvr_buffer_queue.cpp
+++ b/libs/vr/libdvr/dvr_buffer_queue.cpp
@@ -151,7 +151,7 @@
 
 int DvrWriteBufferQueue::GainBuffer(int timeout,
                                     DvrWriteBuffer** out_write_buffer,
-                                    DvrNativeBufferMetadata* out_meta,
+                                    DvrNativeBufferMetadata* /* out_meta */,
                                     int* out_fence_fd) {
   DvrWriteBuffer write_buffer;
   int fence_fd;
@@ -438,7 +438,7 @@
 }
 
 int DvrReadBufferQueue::ReleaseBuffer(DvrReadBuffer* read_buffer,
-                                      const DvrNativeBufferMetadata* meta,
+                                      const DvrNativeBufferMetadata* /* meta */,
                                       int release_fence_fd) {
   LOG_FATAL_IF(
       (read_buffers->slot < 0 || read_buffers->slot >= read_buffers_size()),