Add missing default constructors

Metalava was accidentally including default constructors in the API
generated for CorePlatformApi and IntraCoreApi annotations. This change
adds the constructor and appropriate annotations to allow the metalava
bug to be fixed without changing the API.

Tested by building the API with and without the Metalava fix and
checking that they were the same apart from removing the constructors
for the following classes as they are not required in the API because
the classes are never meant to be instantiated:
* dalvik.system.VMSTack
* libcore.icu.ICU
* libcore.io.DropBox
* libcore.io.EventLogger
* libcore.net.MimeUtils
* libcore.util.SneakyThrow

Bug: 119859108
Test: see above
Change-Id: I87cdb60827edbc2703b9b8723e873aa49c82d9cf
11 files changed