Ensure test suite compiles.

Adding new methods to problem class, and using the Context API for the
BlackoilIntensiveQuantities' porosity update.

opm/models/blackoil/blackoilintensivequantities.hh

@@ -451,7 +451,7 @@ public:
         }
 
         // retrieve the porosity from the problem
-        referencePorosity_ = problem.porosity(globalSpaceIdx, timeIdx);
+        referencePorosity_ = problem.porosity(elemCtx, dofIdx, timeIdx);
         porosity_ = referencePorosity_;
 
         // the porosity must be modified by the compressibility of the

opm/models/blackoil/blackoilproblem.hh

@@ -130,6 +130,12 @@ public:
                                unsigned) const
     { return 0.0; }
 
+    /*!
+     * \brief Returns the compressibility of the porous medium of a cell
+     */
+    Scalar rockCompressibility(unsigned) const
+    { return 0.0; }
+
     /*!
      * \brief Returns the reference pressure for rock the compressibility of a cell
      */
@@ -139,6 +145,12 @@ public:
                                  unsigned) const
     { return 1e5; }
 
+    /*!
+     * \brief Returns the reference pressure for rock the compressibility of a cell
+     */
+    Scalar rockReferencePressure(unsigned) const
+    { return 1e5; }
+
     /*!
      * \brief Returns the reference temperature
      *
@@ -159,6 +171,11 @@ public:
                                   unsigned) const
     { return 1.0; }
 
+    template <class LhsEval>
+    LhsEval rockCompTransMultiplier(const IntensiveQuantities&,
+                                    unsigned) const
+    { return 1.0; }
+
 private:
     //! Returns the implementation of the problem (i.e. static polymorphism)
     Implementation& asImp_()