Migrate build system from Intel oneAPI to AMD AOCC/AOCL toolchain

- Add TOOLCHAIN=aocc option with flang/clang++/mpicxx compilers
- Replace Intel flags (-xHost/-fma/-ipo/-qopenmp) with AOCC flags
  (-march=znver5/-ffast-math/-flto/-fopenmp) targeting EPYC 9755
- Replace Intel oneMKL with AMD AOCL (BLIS + libFLAME + amdlibm)
- Replace Intel TBBMALLOC with system jemalloc
- Change MKL-specific headers to standard CBLAS/LAPACKE
  (TwoPunctures.C, gaussj.C)
- Guard TBBMALLOC to Intel toolchain only

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

AMSS_NCKU_source/gaussj.C

@@ -17,8 +17,8 @@ using namespace std;
 #include <math.h>
 #endif
 
-// Intel oneMKL LAPACK interface
-#include <mkl_lapacke.h>
+// LAPACKE interface (AOCL for AOCC, oneMKL for Intel)
+#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