Apply clang-tidy fixes for performance-unnecessary-value-param in Matrix.cpp (NFC)

Author: joker-eph

mlir/include/mlir/Analysis/Presburger/Matrix.h

@@ -318,7 +318,7 @@ class FracMatrix : public Matrix<Fraction> {
   // The parameter is what [the original
   // paper](https://www.cs.cmu.edu/~avrim/451f11/lectures/lect1129_LLL.pdf)
   // calls `y`, usually 3/4.
-  void LLL(Fraction delta);
+  void LLL(const Fraction &delta);
 
   // Multiply each row of the matrix by the LCM of the denominators, thereby
   // converting it to an integer matrix.

mlir/lib/Analysis/Presburger/Matrix.cpp

@@ -717,7 +717,7 @@ FracMatrix FracMatrix::gramSchmidt() const {
 // Otherwise, we swap b_k and b_{k-1} and decrement k.
 //
 // We repeat this until k = n and return.
-void FracMatrix::LLL(Fraction delta) {
+void FracMatrix::LLL(const Fraction &delta) {
   MPInt nearest;
   Fraction mu;