[llvm] Revert "[APInt] Remove multiplicativeInverse with explicit modulus (#… (PR #87812)

[Jay Foad via llvm-commits]

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@@ -1740,6 +1740,9 @@ class [[nodiscard]] APInt {
     return *this;
   }
 
+  /// \returns the multiplicative inverse for a given modulo.
+  APInt multiplicativeInverse(const APInt &modulo) const;
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jayfoad wrote:

Variable names should use CamelCase, throughout.

https://github.com/llvm/llvm-project/pull/87812