[LLVM] Make MachineBlockFrequencyInfo's constructor arguments const (NFC) (#149279)

This avoids having to call `MachineBlockFrequencyInfo::calculate`
manually if one of the parameters is const.

Author: lucas-rami

llvm/include/llvm/CodeGen/MachineBlockFrequencyInfo.h

@@ -39,8 +39,8 @@ class MachineBlockFrequencyInfo {
 public:
   LLVM_ABI MachineBlockFrequencyInfo(); // Legacy pass manager only.
   LLVM_ABI explicit MachineBlockFrequencyInfo(
-      MachineFunction &F, MachineBranchProbabilityInfo &MBPI,
-      MachineLoopInfo &MLI);
+      const MachineFunction &F, const MachineBranchProbabilityInfo &MBPI,
+      const MachineLoopInfo &MLI);
   LLVM_ABI MachineBlockFrequencyInfo(MachineBlockFrequencyInfo &&);
   LLVM_ABI ~MachineBlockFrequencyInfo();
 

llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp

@@ -202,8 +202,8 @@ MachineBlockFrequencyInfo::MachineBlockFrequencyInfo(
     MachineBlockFrequencyInfo &&) = default;
 
 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo(
-    MachineFunction &F, MachineBranchProbabilityInfo &MBPI,
-    MachineLoopInfo &MLI) {
+    const MachineFunction &F, const MachineBranchProbabilityInfo &MBPI,
+    const MachineLoopInfo &MLI) {
   calculate(F, MBPI, MLI);
 }