Fixup the constructor/destructor function names again (they should be _init()
and _fini() it seems, and not being called caused sandbox_lib_path to be
unset, and thus breaking the execve() wrapper's LD_PRELOAD protection).
Add both the path in given SANDBOX_x variable, as well as its symlink
resolved path in init_env_entries(). Modify filter_path() to be able to
resolve paths without resolving symlinks, as well as to be able to resolve
symlinks. Fix a possible segfault in check_access(). Add symlink resolving
to check_access() resolving bug #31019. Add 'hack' for unlink, as the fix
for bug #31019 cause access violations if we try to remove a symlink that is
not in protected path, but points to a protected path. Fix a memory leak in
sandbox.c (sandbox_pids_file in main()). Fix the realpath() calls in main()
(sandbox.c) being unchecked. Fix the debug logname not having the pid in it
(pid_string was uninitialized). General syntax cleanups.