Prevent race condition in font export directory making (issue 319510043 by address@hidden)

[dak]

https://codereview.appspot.com/319510043/diff/1/scm/framework-ps.scm
File scm/framework-ps.scm (right):

https://codereview.appspot.com/319510043/diff/1/scm/framework-ps.scm#newcode551
scm/framework-ps.scm:551: (let ((errno (system-error-errno stuff)))
This is just
(if (= EEXIST (system-error-errno stuff))
   (ly:debug ...)
  (throw 'system-error (cdr stuff)))

https://codereview.appspot.com/319510043/