Replace MKL with OpenBLAS

- TwoPunctures.C: <mkl_cblas.h> → <cblas.h>
- gaussj.C: <mkl_lapacke.h> → <lapacke.h>
- makefile.inc: use -lopenblaso, remove MKLROOT dependency
- makefile: remove -I${MKLROOT}/include from all flag variables
- Add OpenMPI include path to filein (needed since g++ is used for .C
  compilation, not the mpicxx wrapper)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

AMSS_NCKU_source/TwoPunctures.C

@@ -27,7 +27,7 @@ using namespace std;
 #endif
 
 #include "TwoPunctures.h"
-#include <mkl_cblas.h>
+#include <cblas.h>
 
 TwoPunctures::TwoPunctures(double mp, double mm, double b,
                            double P_plusx, double P_plusy, double P_plusz,