[NFC][CodeGen] Make a few MachineBlockHashInfo functions static (#192825)

Author: vitalybuka

llvm/lib/CodeGen/MachineBlockHashInfo.cpp

@@ -17,7 +17,7 @@
 
 using namespace llvm;
 
-uint64_t hashBlock(const MachineBasicBlock &MBB, bool HashOperands) {
+static uint64_t hashBlock(const MachineBasicBlock &MBB, bool HashOperands) {
   uint64_t Hash = 0;
   for (const MachineInstr &MI : MBB) {
     if (MI.isMetaInstruction() || MI.isTerminator())
@@ -34,7 +34,7 @@ uint64_t hashBlock(const MachineBasicBlock &MBB, bool HashOperands) {
 }
 
 /// Fold a 64-bit integer to a 16-bit one.
-uint16_t fold_64_to_16(const uint64_t Value) {
+static uint16_t fold_64_to_16(const uint64_t Value) {
   uint16_t Res = static_cast<uint16_t>(Value);
   Res ^= static_cast<uint16_t>(Value >> 16);
   Res ^= static_cast<uint16_t>(Value >> 32);