Support nice logging for ProgramPoint* in dataflow log (llvm#154839)

There're places where a pointer instead of `ProgramPoint` object is
passed to stream print `<<`, and they'll be printed as pointer value.
This PR converts them to object before passing to stream printers.

The address isn't much helpful in the debug and does not help when
diffing before/after debug traces.

Author: pchen7e2

mlir/lib/Analysis/DataFlowFramework.cpp

@@ -45,7 +45,7 @@ void AnalysisState::addDependency(ProgramPoint *dependent,
   DATAFLOW_DEBUG({
     if (inserted) {
       LDBG() << "Creating dependency between " << debugName << " of " << anchor
-             << "\nand " << debugName << " on " << dependent;
+             << "\nand " << debugName << " on " << *dependent;
     }
   });
 }
@@ -128,7 +128,7 @@ LogicalResult DataFlowSolver::initializeAndRun(Operation *top) {
     worklist.pop();
 
     DATAFLOW_DEBUG(LDBG() << "Invoking '" << analysis->debugName
-                          << "' on: " << point);
+                          << "' on: " << *point);
     if (failed(analysis->visit(point)))
       return failure();
   }