path to readex.h should be defined in FOAMMODULES

OpenFOAM-v1612+/applications/solvers/incompressible/icoFoam/Make/options

 EXE_INC = \
     -I$(LIB_SRC)/finiteVolume/lnInclude \
     -I$(LIB_SRC)/meshTools/lnInclude  \
-    -I$(HOME)/OpenFOAM/meric/include -DWITHREADEX $(READEX_DEFINE)
+    $(READEX_INCLUDE) -DWITHREADEX $(READEX_DEFINE)
 
 EXE_LIBS = \
     -lfiniteVolume \

OpenFOAM-v1612+/applications/solvers/incompressible/simpleFoam/Make/options

@@ -6,7 +6,7 @@ EXE_INC = \
     -I$(LIB_SRC)/finiteVolume/lnInclude \
     -I$(LIB_SRC)/meshTools/lnInclude \
     -I$(LIB_SRC)/sampling/lnInclude \
-    -I$(HOME)/OpenFOAM/meric/include \
+    $(READEX_INCLUDE) \
     -DWITHREADEX $(READEX_DEFINE)
 
 

OpenFOAM-v1612+/src/OpenFOAM/Make/options

 EXE_INC = -I$(OBJECTS_DIR) \
--I$(HOME)/OpenFOAM/meric/include -DWITHREADEX $(READEX_DEFINE)
+ -DWITHREADEX $(READEX_DEFINE) $(READEX_INCLUDE)
 
 LIB_LIBS = \
     $(FOAM_LIBBIN)/libOSspecific.o \

OpenFOAM-v1612+/src/Pstream/mpi/Make/options

 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
 sinclude $(RULES)/mplib$(WM_MPLIB)
 
-EXE_INC  = $(PFLAGS) $(PINC) $(c++LESSWARN)  -I$(HOME)/OpenFOAM/meric/include -DWITHREADEX $(READEX_DEFINE)
+EXE_INC  = $(PFLAGS) $(PINC) $(c++LESSWARN)  $(READEX_INCLUDE) -DWITHREADEX $(READEX_DEFINE)
 
 LIB_LIBS = $(PLIBS) \
 	$(READEX_LIBS)