Add thread-safe ShellPatch::setupintintstuff with OpenMP

Split prolongpointstru into search-only (prolongpointstru_search) and
append-only (prolongpointstru_append) functions. The search is read-only
and thread-safe; each thread builds private linked lists via
prolongpointstru_append, merged after the parallel loop.

This eliminates critical-section contention and delivers ~2.2x speedup:
setupintintstuff: 511s -> 252s, total init: 592s -> 267s.

Also add -qopenmp to ShellPatch.o compilation via makefile override rule
and <omp.h> include with _OPENMP guards + fallback stubs.

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

AMSS_NCKU_source/makefile

@@ -73,6 +73,10 @@ endif
 .C.o:
 	${CXX} $(CXXAPPFLAGS) -c $< $(filein) -o $@
 
+# ShellPatch.C uses OpenMP for setupintintstuff search loops
+ShellPatch.o: ShellPatch.C
+	${CXX} $(CXXAPPFLAGS) $(OMP_FLAG) -c $< $(filein) -o $@
+
 .for.o:
 	$(f77) -c $< -o $@