[llvm] [DAG] isConstantIntBuildVectorOrConstantInt - peek through bitcasts (PR #112710)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

This change broke compilation for Windows/ARM - some files now make the compiler to not terminate (running for nearly forever, and possibly consuming all memory).

This can be reproduced with https://martin.st/temp/llvm-preproc.cpp, compiled as:
```
$ clang -target armv7-w64-mingw32 -c -O2 llvm-preproc.cpp
```
Previously, this finished compiling in a matter of seconds, now it doesn't finish.

Pushing a revert shortly.



https://github.com/llvm/llvm-project/pull/112710