Fix trivial warnings hidden by -isystem

Fix the trivial warnings that are hidden by the use of -isystem to
include frameworks/av and caught by -Werror.

Test: m -j checkbuild
Bug: 31751828
Change-Id: I155f9f772ce0a84b364313814cb7cf528b9de4eb
Merged-In: I155f9f772ce0a84b364313814cb7cf528b9de4eb
(cherry picked from commit b8c35f94470d1518e2def0582aaec4e038c92af0)
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
index b742762..f8453eb 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
@@ -1028,7 +1028,7 @@
             // (Case 1)
             // Must be a multiple of the frame size.  If it is not a multiple of a frame size, it
             // needs to fail, as we should not carry over fractional frames between calls.
-            CHECK_EQ(copy % mAudioSink->frameSize(), 0);
+            CHECK_EQ(copy % mAudioSink->frameSize(), 0u);
 
             // (Case 2, 3, 4)
             // Return early to the caller.