BQ: fix some uninitialized variables

Bug 27555981
Bug 27556038

Change-Id: I436b6fec589677d7e36c0e980f6e59808415dc0e
diff --git a/libs/gui/IGraphicBufferConsumer.cpp b/libs/gui/IGraphicBufferConsumer.cpp
index dc917a8..590a25e 100644
--- a/libs/gui/IGraphicBufferConsumer.cpp
+++ b/libs/gui/IGraphicBufferConsumer.cpp
@@ -478,7 +478,7 @@
         } break;
         case GET_RELEASED_BUFFERS: {
             CHECK_INTERFACE(IGraphicBufferConsumer, data, reply);
-            uint64_t slotMask;
+            uint64_t slotMask = 0;
             status_t result = getReleasedBuffers(&slotMask);
             reply->writeInt64(slotMask);
             reply->writeInt32(result);