[clang] [Clang][LoongArch] Fixed incorrect _BitInt(N>64) alignment (PR #145297)

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Ami-zhang wrote:

> LGTM. BTW, could you please mention this change in clang's release note?

Should we submit a separate PR later to document the major changes from this development cycle in the release notes? Similar to what was done in commit 3c7a878d919c6483c9e78a3ed4578d4ee2f54408.

https://github.com/llvm/llvm-project/pull/145297