[clang] [Clang][Sema] fix outline member function template with default align crash (PR #78400)

[Qizhi Hu via cfe-commits]

jcsxky wrote:

> @jcsxky this patch introduced a regression. Please see the reproducer here: https://godbolt.org/z/rEfWP75Ta. It compiles before this change and fails at this change. It also compiles with gcc and clang-17.

Sorry for importing new bugs. @erichkeane Could you help me revert this patch in order to not influence others since I am not familiar with github reverting operation? I afraid I would spent a long time to look into the root cause of the issue. Appreciate for you help and many thanks!

https://github.com/llvm/llvm-project/pull/78400