define-fringe-bitmap is not always available

[David Holm]

When Emacs is built without Cocoa or X on MacOS X it doesn't include the function define-fringe-bitmap causing Mingus to fail during load. The same issue was identified in flycheck/flycheck#57.

Debugger entered--Lisp error: (void-function define-fringe-bitmap)
(define-fringe-bitmap (quote mingus-NP-fringe) [128 192 224 240 248 252 248 240 224 192 128])
ad-Orig-require(mingus nil nil)
require(mingus)                                                                                                    
eval-buffer(#<buffer  *load*-493821> nil "/Users/dholm/.emacs.d/el-get/mingus/mingus-stays-home.el" nil t)  ; Reading at buffer position 6310
load-with-code-conversion("/Users/dholm/.emacs.d/el-get/mingus/mingus-stays-home.el" "/Users/dholm/.emacs.d/el-get/mingus/mingus-stays-home.el" nil t)
ad-Orig-require(mingus-stays-home nil nil)
require(mingus-stays-home)

[David Holm]

I just confirmed that the same issue exists even on Linux when built without GUI support.

[Niels Giesen]

Guarding added in commit e03483a,