Fix/suppress google-explicit-constructor warnings

* Add explicit to conversion constructors/operators

Bug: 28341362
Test: make with WITH_TIDY=1 DEFAULT_GLOBAL_TIDY_CHECKS=-*,google-explicit-constructor
Change-Id: Iac8f3aa14cd04861f6bcbab56b0dfc28c9a89e53
diff --git a/include/input/KeyCharacterMap.h b/include/input/KeyCharacterMap.h
index 33d2757..5e542b8 100644
--- a/include/input/KeyCharacterMap.h
+++ b/include/input/KeyCharacterMap.h
@@ -196,7 +196,7 @@
         };
 
         struct Property {
-            inline Property(int32_t property = 0, int32_t metaState = 0) :
+            inline explicit Property(int32_t property = 0, int32_t metaState = 0) :
                     property(property), metaState(metaState) { }
 
             int32_t property;