[proof] Deprecate PROOF and PROOFLITE with warnings

since the tools will be removed in 6.38.00. RDataFrame and DistRDF
can be used instead.

Author: dpiparo

Diff for: proof/proof/inc/TProof.h

@@ -1071,7 +1071,7 @@ friend class TXProofServ;     // to access EUrgent
    static Int_t         GetParameter(TCollection *c, const char *par, Double_t &value);
 
    ClassDefOverride(TProof,0)  //PROOF control class
-};
+} R__DEPRECATED(6,38, "Legacy interactive distributed processing engine. Use RDataFrame and DistRDF instead.");
 
 // Global object with default PROOF session
 R__EXTERN TProof *gProof;

Diff for: proof/proof/inc/TProofLite.h

@@ -168,6 +168,6 @@ friend class TProofPlayerLite;
    static Int_t GetNumberOfWorkers(const char *url = 0);
 
    ClassDefOverride(TProofLite,0)  //PROOF-Lite control class
-};
+} R__DEPRECATED(6,38, "Legacy interactive distributed processing engine. Use RDataFrame instead.");
 
 #endif