SurfaceFlinger: Make log message 64-bit compatible

Fixes the build on 64-bit targets that complain about using a size_t
with a %d in a format string

Change-Id: I7dfcd3a49eb0dbc5dffeb82bb7208de7f7925f08
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 828ba9d..6013ddb 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2009,7 +2009,7 @@
             ++blameCounts[blame.second];
         }
 
-        ALOGI("FD Blame: %d open fds", currentFds.size());
+        ALOGI("FD Blame: %zu open fds", currentFds.size());
         for (auto blame : blameCounts) {
             std::string layers;
             for (auto layer : blame.first) {