[RecursiveASTVisitor] Fix RecursiveASTVisitor (RAV) fails to visit the...

[RecursiveASTVisitor] Fix RecursiveASTVisitor (RAV) fails to visit the initializer of a bitfield (#69557)

The problem was introduced in the commit
https://github.com/llvm/llvm-project/commit/6b8e3c02ca44fb6c3738bb0c75859c11a03e30ed
when the possibility of initialized bitfields was added, but the logic
in RecursiveASTVisitor was not updated. This PR fixed that.

This fixes https://github.com/llvm/llvm-project/issues/64916

.

Patch by Scott McPeak

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Co-authored-by: cor3ntin <corentinjabot@gmail.com>