[gimp] gitlab-ci: disable building file-mng for gimp-win32 explicitly.

[Jehan <jehanp src gnome org>]

commit fc4fedeb686217959a6e4f7559f49eaa4385e422
Author: Jehan <jehan girinstud io>
Date:   Sat Dec 5 21:43:27 2020 +0100

    gitlab-ci: disable building file-mng for gimp-win32 explicitly.
    
    We were not building it by not installing libmng until now. But graphviz
    must have pulled libmng. So disable explicitly the option in GIMP
    configure step.

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index dcbf83cdf2..061aa25e1f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -284,7 +284,7 @@ gimp-win32:
     - export PATH="`pwd`/.local/bin:$PATH"
     - mkdir _build && cd _build
     - echo 'crossroad meson ..
-              -Dwmf=disabled  -Dgtk-doc=false && ninja install &&
+              -Dwmf=disabled  -Dmng=disabled -Dgtk-doc=false && ninja install &&
             cp -fr $CROSSROAD_PREFIX/ ../gimp-prefix/
             ' |
       crossroad w32 gimp --run="-"