resolve symlinks when serving 9p
resolve symlinks when serving 9p

Using a symbolic link for a root directory caused 9p to return an
`"Unknown error 526"` error. This commit evaluates symlinks before
passing paths to the filesystem.

Signed-off-by: Ben Johnson <55d7f4a712d221ae5ab8eebc7a76203699f64e08@yahoo.com>

flynn/bake