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/makefile

@@ -43,10 +43,10 @@ ESCALAR_KERNEL_FLAG = -DBSSN_USE_ESCALAR_C_KERNEL=$(EFFECTIVE_USE_CXX_ESCALAR_KE
 ## GCC build flags (optimized for x86-64-v4)
 ## PGO disabled (used negative optimization on Intel; not tested on GCC)
 CXXAPPFLAGS = -O3 -march=x86-64-v4 -ffast-math -mfma -flto \
-              -Dfortran3 -Dnewc -I${MKLROOT}/include $(INTERP_LB_FLAGS) \
+              -Dfortran3 -Dnewc $(INTERP_LB_FLAGS) \
               $(TRANSFER_CACHE_FLAG) $(ESCALAR_KERNEL_FLAG)
 f90appflags = -O3 -march=x86-64-v4 -ffast-math -mfma -flto \
-              -cpp -I${MKLROOT}/include $(POLINT6_FLAG)
+              -cpp $(POLINT6_FLAG)
 
 .SUFFIXES: .o .f90 .C .for .cu
 
@@ -89,7 +89,7 @@ z4c_rhs_c.o: z4c_rhs_c.C
 
 ## TwoPunctureABE flags (no PGO; PGO was negative optimization)
 TP_OPTFLAGS = -O3 -march=x86-64-v4 -ffast-math -mfma -flto \
-              -Dfortran3 -Dnewc -I${MKLROOT}/include
+              -Dfortran3 -Dnewc
 
 TwoPunctures.o: TwoPunctures.C
 	${CXX} $(TP_OPTFLAGS) -fopenmp -c $< -o $@