Make ctests platform independent

Windows doesn't have a mechanism similar to rpaths. Instead, shared
libraries are searched in the current working directory and  in the
directory with the executable followed by directories in the environment
variable PATH.

Add the path to the shared libarpack library to PATH for ctests that run
executables that are located in a different directory and that set the
current working directory not to the directory with the libarpack.dll.
Use a generator expression that should be working independent on the CMake
generator.

CMakeLists.txt

@@ -711,6 +711,11 @@ function(build_tests)
       configure_file(EXAMPLES/MATRIX_MARKET/issue215.mtx ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/issue215.mtx)
       configure_file(EXAMPLES/MATRIX_MARKET/issue215.sh ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/issue215.sh)
       add_test(NAME issue215_tst WORKING_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY} COMMAND ${BASH_PROGRAM} issue215.sh)
+      if (WIN32 AND BUILD_SHARED_LIBS)
+        set_tests_properties(arpackmm_tst issue401_tst issue215_tst
+          PROPERTIES
+          ENVIRONMENT_MODIFICATION "PATH=path_list_prepend:$<TARGET_FILE_DIR:arpack>")
+      endif()
     endif()
 
     if (PYTHON3)