[gegl] tests: only run gegl test if cairo installed

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 1d6a3b26a1379c3086de96b156fc29d5897e7452
Author: John <jtm home gmail com>
Date:   Fri Feb 12 14:20:51 2021 +0000

    tests: only run gegl test if cairo installed

 tests/compositions/meson.build | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/tests/compositions/meson.build b/tests/compositions/meson.build
index b5d0de486..fb1fda83f 100644
--- a/tests/compositions/meson.build
+++ b/tests/compositions/meson.build
@@ -20,7 +20,6 @@ composition_tests = [
   'exposure',
   'fattal02',
   'gamma',
-  'gegl',
   'grey-json',
   'hdr-color',
   'illusion',
@@ -50,6 +49,9 @@ composition_tests = [
   'transform',
   'weighted-blend',
 ]
+if cairo.found()
+  composition_tests += 'gegl'
+endif
 if libumfpack.found()
   composition_tests += 'matting-levin'
 endif