Seuquential version finished. Start with MPI stuff

Does not compile.

mk/include_CLANG.mk

@@ -1,7 +1,13 @@
+ifeq ($(strip $(ENABLE_MPI)),true)
 CC   = mpicc
+DEFINES  = -D_MPI
+else
+CC = clang
+endif
+
 LD   = $(CC)
 
-ifeq ($(ENABLE_OPENMP),true)
+ifeq ($(strip $(ENABLE_OPENMP)),true)
 OPENMP   = -fopenmp
 #OPENMP   = -Xpreprocessor -fopenmp #required on Macos with homebrew libomp
 LIBS     = # -lomp
@@ -11,5 +17,5 @@ VERSION  = --version
 CFLAGS   = -Ofast -std=c99 $(OPENMP)
 #CFLAGS   = -Ofast -fnt-store=aggressive  -std=c99 $(OPENMP) #AMD CLANG
 LFLAGS   = $(OPENMP)
-DEFINES  = -D_GNU_SOURCE
-INCLUDES = -I~/.local/include
+DEFINES  += -D_GNU_SOURCE
+INCLUDES = -I/Users/jan/.local/include