[llvm] [ADT] Reinstate "Refactor Bitset to Be More Constexpr-Usable" (PR #189497)

[Jiachen Yuan via llvm-commits]

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@@ -16,31 +16,41 @@
 #ifndef LLVM_ADT_BITSET_H
 #define LLVM_ADT_BITSET_H
 
+#include "llvm/ADT/STLExtras.h"
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JiachenYuan wrote:

Right, thanks for catching it! `STLExtras.h` is too heavy. The refactored code uses `popcount`, which requires `bit.h`. I have changed the include accordingly.

https://github.com/llvm/llvm-project/pull/189497