Fix Overflow and Range errors

Current code works in 10.3.3
Unknown in 10.4.2
TRandom.Next overflows 64 bits in 11 & 12
And Range error in NextBytes with UInt32 returned to an Integer variable (Rnd)

Author: pmcgee69

Source/Velthuis.RandomNumbers.pas

@@ -103,14 +103,25 @@ constructor TRandom.Create(Seed: Int64);
 
 function TRandom.Next(Bits: Integer): UInt32;
 begin
-{$IFOPT Q+}
+{$IFOPT R+}
 {$DEFINE HasRangeChecks}
 {$ENDIF}
-  FSeed := (FSeed * CMultiplier + CIncrement);
-  Result := UInt32(FSeed shr (64 - Bits)); // Use the highest bits; Lower bits have lower period.
+{$IFOPT Q+}
+{$DEFINE HasOverflowChecks}
+{$ENDIF}
+
+{$RANGECHECKS OFF}
+{$OVERFLOWCHECKS OFF}
+
+  FSeed := Int64(FSeed * CMultiplier + CIncrement);
+  Result:= UInt32(FSeed shr (64 - Bits)); // Use the highest bits; Lower bits have lower period.
+
 {$IFDEF HasRangeChecks}
 {$RANGECHECKS ON}
 {$ENDIF}
+{$IFDEF HasOverflowChecks}
+{$OVERFLOWCHECKS ON}
+{$ENDIF}
 end;
 
 function TRandom.GetSeed: Int64;
@@ -161,7 +172,8 @@ constructor TRandomBase.Create;
 procedure TRandomBase.NextBytes(var Bytes: array of Byte);
 var
   Head, Tail: Integer;
-  N, Rnd, I: Integer;
+  N, I: Integer;
+  Rnd: UInt32;
 begin
   Head := Length(Bytes) div SizeOf(Int32);
   Tail := Length(Bytes) mod SizeOf(Int32);