arpackmm: improve command line for testing. #561

Job	Run time
ubuntu_latest_cmake_install	9m 57s
ubuntu_latest_cmake	3m 51s
ubuntu_latest_autotools	9m 52s
ubuntu_latest_autotools_install	16m 10s
macos_latest_cmake	4m 18s
macos_latest_cmake_python	3m 50s
ubuntu_latest_autotools_ilp64	1m 31s
ubuntu_latest_cmake_python	11m 49s
macos_latest_autotools	7m 27s
MinGW-w64 UCRT64 INTERFACE64=ON/MPI=OFF	5m 47s
MinGW-w64 UCRT64 INTERFACE64=OFF/MPI=ON	5m 51s
MinGW-w64 UCRT64 INTERFACE64=OFF/MPI=OFF	5m 33s
MinGW-w64 CLANG64 INTERFACE64=ON/MPI=OFF	4m 51s
MinGW-w64 CLANG64 INTERFACE64=OFF/MPI=ON	5m 13s
MinGW-w64 CLANG64 INTERFACE64=OFF/MPI=OFF	4m 58s
	1h 40m 58s

Provide feedback