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/tests/LayerCallback_test.cpp b/services/surfaceflinger/tests/LayerCallback_test.cpp
index 7a5ed48..6d28e62 100644
--- a/services/surfaceflinger/tests/LayerCallback_test.cpp
+++ b/services/surfaceflinger/tests/LayerCallback_test.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 "LayerTransactionTest.h"
 #include "utils/CallbackUtils.h"
 
@@ -870,3 +874,6 @@
     EXPECT_NO_FATAL_FAILURE(waitForCallback(callback, expected, true));
 }
 } // namespace android
+
+// TODO(b/129481165): remove the #pragma below and fix conversion issues
+#pragma clang diagnostic pop // ignored "-Wconversion"