[Fixed Point] Fix C++20 compilation error

[antoniofrighetto]

Summary

Due to how operator== changed after operator<=> landing in C++20 (error: use of overloaded operator '==' is ambiguous (with operand types 'const llvm::APSInt' and 'const unsigned long')), CheckIntPartMin/CheckIntPartMax interfaces are now leveraging APSInt::compareValues.

[aaron.ballman]

LGTM assuming pre-commit CI doesn't find any unexpected surprises. Thanks for the cleanup!

[aaron.ballman]

The precommit CI test failures are unrelated, so this LGTM now, thank you!

llvm/unittests/ADT/APFixedPointTest.cpp

void CheckIntPart(const FixedPointSemantics &Sema, int64_t IntPart) {
   if (Sema.isSigned()) {
     APFixedPoint Negative(
         APInt(Sema.getWidth(), (IntPart << Scale), Sema.isSigned()), Sema);
     ASSERT_EQ(Negative.getIntPart(), IntPart);
   }
 }
 
 void CheckIntPartMin(const FixedPointSemantics &Sema, int64_t Expected) {
-  ASSERT_EQ(APFixedPoint::getMin(Sema).getIntPart(), Expected);
+  EXPECT_TRUE(APSInt::compareValues(APFixedPoint::getMin(Sema).getIntPart(),
+                                    APSInt::get(Expected)) == 0);
 }
 
 void CheckIntPartMax(const FixedPointSemantics &Sema, uint64_t Expected) {
-  ASSERT_EQ(APFixedPoint::getMax(Sema).getIntPart(), Expected);
+  EXPECT_TRUE(APSInt::compareValues(APFixedPoint::getMax(Sema).getIntPart(),
+                                    APSInt::getUnsigned(Expected)) == 0);
 }
 
 TEST(FixedPoint, getIntPart) {
   // Normal values
   CheckIntPart(getSAccumSema(), 2);
   CheckIntPart(getAccumSema(), 2);
   CheckIntPart(getLAccumSema(), 2);
   CheckIntPart(getUSAccumSema(), 2);