[llvm] [NFC] Fix MSVC C4146 warnings in LLVM headers and tools (PR #225577)

[Younes Yazami via llvm-commits]

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@@ -378,7 +378,7 @@ class MemoryDepChecker {
   /// operate on simultaneously, multiplied by the size of the element in bits.
   /// The size of the element is taken from the memory access that is most
   /// restrictive.
-  uint64_t MaxSafeVectorWidthInBits = -1U;
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yelidris-public wrote:

I believe the semantic intent is the same, I could adjust it to:
`uint64_t MaxSafeVectorWidthInBits  =
      std::numeric_limits<uint64_t>::max();`
if that's preferred.
And I believe C4146 cleanup for MSVC warnings is something that was done before.
#155192, and #147439

https://github.com/llvm/llvm-project/pull/225577