[clang] [AST] Use APIntStorage to fix memory leak in EnumConstantDecl. (PR #78311)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

LGTM thank you for the fix! I'm on the fence about this getting a release note, but leaning towards mentioning it as fixing a memory leak (I don't expect this to be observable for most folks because cleaning up the ASTContext generally means quitting the process but it would be observable for folks using Clang as a library).

https://github.com/llvm/llvm-project/pull/78311