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/gaussj.C

@@ -18,7 +18,7 @@ using namespace std;
 #endif
 
 // Intel oneMKL LAPACK interface
-#include <mkl_lapacke.h>
+#include <lapacke.h>
 /* Linear equation solution using Intel oneMKL LAPACK.
 a[0..n-1][0..n-1] is the input matrix. b[0..n-1] is input
 containing the right-hand side vectors. On output a is