return_status::checkStatus => assertOk

checkStatus doesn't really set mCheckStatus to true, and hence is
a misnomer. Change it to assertOk (correspond to isOk()).

And hence the move assignment operator should not call checkStatus
(because it is valid to move into a Return<T> object that !isOk()
but has mCheckedStatus to true), because caller is fully aware of
the error that will be overwritten.

Test: libhidl_test
Change-Id: I86a44967b68619d1467d2cc9caaa39124b156121
diff --git a/base/include/hidl/Status.h b/base/include/hidl/Status.h
index 2f26ffa..c5c5bd9 100644
--- a/base/include/hidl/Status.h
+++ b/base/include/hidl/Status.h
@@ -147,7 +147,7 @@
         Status mStatus {};
         mutable bool mCheckedStatus = false;
     protected:
-        void checkStatus() const;
+        void assertOk() const;
     public:
         return_status() {}
         return_status(Status s) : mStatus(s) {}
@@ -158,12 +158,7 @@
         return_status(return_status &&other) {
             *this = std::move(other);
         }
-        return_status &operator=(return_status &&other) {
-            checkStatus();
-            std::swap(mStatus, other.mStatus);
-            std::swap(mCheckedStatus, other.mCheckedStatus);
-            return *this;
-        }
+        return_status &operator=(return_status &&other);
 
         ~return_status();
 
@@ -196,7 +191,7 @@
     ~Return() = default;
 
     operator T() const {
-        checkStatus();
+        assertOk();
         return mVal;
     }
 
@@ -222,7 +217,7 @@
     ~Return() = default;
 
     operator sp<T>() const {
-        checkStatus();
+        assertOk();
         return mVal;
     }
 };