mlir/Presburger: guard dump function; fix buildbot (#95218)
Follow up on 76030dc (mlir/Presburger/MPInt: move into llvm/ADT) to
guard a function in Fraction.h with !NDEBUG || LLVM_ENABLE_DUMP, since
the call to the corresponding function in DynamicAPInt is guarded
similarly. This patch fixes the build when mlir is built with this
configuration.