SurfaceFlinger: Enable -WConversion in Android.bp

Enable global -WConversion in Android.bp and turn it off in
individual files. This is the first step to enable -WConversion
in SurfaceFlinger.

Test: boot
Bug: 129481165
Change-Id: Ia752df39ef380bde71705a32582d618242c466f7
diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index 6e28167..01413b9 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -14,6 +14,10 @@
  * limitations under the License.
  */
 
+// TODO(b/129481165): remove the #pragma below and fix conversion issues
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wconversion"
+
 #include <thread>
 
 #include <android-base/stringprintf.h>
@@ -1058,3 +1062,6 @@
 
 } // namespace impl
 } // namespace android::compositionengine
+
+// TODO(b/129481165): remove the #pragma below and fix conversion issues
+#pragma clang diagnostic pop // ignored "-Wconversion"