ports-mgmt/synth: Upgrade version 1.21 => 1.22

Two minor bug fixes:

• A specific check during test mode would emit a failure to stdout when testing devel/py-setuptools27. It turns out that there's a file there with a space in the filename. The filename was an argument for /usr/bin//file and it wasn't escaped. The file in question had parentheses too which the shell was trying to process. The fix was to escape the filename in the /usr/bin/file command.
• The builders were mounting the source directory from "/usr/src", not $sysroot/usr/src as intended. This potentially causes breakage when the $sysroot reflects a different versions/release than the host machine has (e.g. making FreeBSD 10.2 packages on FreeBSD 11-current). Now the source directory mount is relative to profile's $sysroot.