fuse_sqlfs: support giving a password via stdin
fuse_sqlfs: support giving a password via stdin

This makes it easier to mount encrypted vfs files, rather than editing code
and compiling it ;)

closes #1826 https://dev.guardianproject.info/issues/1826
https://dev.guardianproject.info/projects/iocipher/wiki

guardianproject/libsqlfs,eighthave/libsqlfs,spthaolt/libsqlfs,spthaolt/libsqlfs,eighthave/libsqlfs,guardianproject/libsqlfs,spthaolt/libsqlfs,eighthave/libsqlfs,guardianproject/libsqlfs,guardianproject/libsqlfs,guardianproject/libsqlfs,eighthave/libsqlfs,eighthave/libsqlfs,spthaolt/libsqlfs,spthaolt/libsqlfs