[MLIR][Presburger] introduce MPInt to support fast arbitrary precision in Presburger

This uses an int64_t-based fastpath for the common case and falls back to
SlowMPInt to handle the rare cases where larger numbers occur.
It uses `__builtin_*` for performance through the support in LLVM MathExtras.

Using this in the Presburger library results in a minor performance
*improvement* over any commit hash before sequence of patches
starting at d5e31cf38adfc2c240fb9717989792537cc9e819.

This was previously reverted in 1e10d35ea9c02e9b5694836fd3dcc0b9baf28b48 due
to a build failure; relanding now with an attempted fix.

Reviewed By: Groverkss, ftynse

Differential Revision: https://reviews.llvm.org/D128811

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