Fix a (false positive?) Argument cannot be negative coverity defect.

Rather than guarding close(fd) with an fd >= 0 test and setting fd
to -1 when it is closed to avoid a potential double-close, just
move the close() call after the conditional "goto make_token". This
moves the close() call totally outside the loop to avoid the
possibility of calling it twice. This should also prevent a Coverity
warning about checking fd for validity after it was previously passed
to read().

Reported by: Coverity
CID: 1355335
MFC after: 1 week
X-MFC with: r299484