[gegl] meson: add optional dependency to maxflow

[Thomas Manni <tmanni src gnome org>]

commit 8bed3473f730373045f269b1340c421b0ed428fe
Author: Thomas Manni <thomas manni free fr>
Date:   Tue Nov 3 19:12:05 2020 +0100

    meson: add optional dependency to maxflow

 meson.build       | 4 ++++
 meson_options.txt | 1 +
 2 files changed, 5 insertions(+)
---
diff --git a/meson.build b/meson.build
index c661496c5..23a9b2400 100644
--- a/meson.build
+++ b/meson.build
@@ -244,6 +244,9 @@ mrg       = dependency('mrg',         version: '>=0.1.4',
 )
 config.set('HAVE_MRG', mrg.found())
 
+maxflow   = dependency('maxflow',     version: '>=3.0.4',
+  required: get_option('maxflow')
+)
 openexr   = dependency('OpenEXR',     version: '>=1.6.1',
   required: get_option('openexr')
 )
@@ -399,5 +402,6 @@ message('\n'.join(['',
 '  umfpack:         @0@'.format(libumfpack.found()),
 '  TIFF             @0@'.format(libtiff.found()),
 '  webp:            @0@'.format(libwebp.found()),
+'  maxflow:         @0@'.format(maxflow.found()),
 '  poly2tri-c:      @0@ (@1@)'.format(poly2tri_c.found(),poly2tri_c.type_name()),
 '']))
diff --git a/meson_options.txt b/meson_options.txt
index 9bc643baa..dd93235ce 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -20,6 +20,7 @@ option('libv4l',        type: 'feature', value: 'auto')
 option('libv4l2',       type: 'feature', value: 'auto')
 option('lua',           type: 'feature', value: 'auto')
 option('mrg',           type: 'feature', value: 'auto')
+option('maxflow',       type: 'feature', value: 'auto')
 option('openexr',       type: 'feature', value: 'auto')
 option('cairo',         type: 'feature', value: 'auto')
 option('pango',         type: 'feature', value: 'auto')