[geary: 2/3] Turn the 'libunwind' build option into a boolean.

[Michael Gratton <mjog src gnome org>]

commit b120525fd6749d8d7061529a200c6f35ff114bb0
Author: Thomas Moschny <thomas moschny gmx de>
Date:   Tue Feb 19 15:40:10 2019 +0100

    Turn the 'libunwind' build option into a boolean.

 meson.build       | 2 +-
 meson_options.txt | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/meson.build b/meson.build
index f0574eeb..0e6d0143 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project('geary', [ 'vala', 'c' ],
   version: '3.32-dev',
   license: 'LGPL2.1+',
-  meson_version: '>= 0.47',
+  meson_version: '>= 0.43',
 )
 
 gnome = import('gnome')
diff --git a/meson_options.txt b/meson_options.txt
index f29b0f0c..63bbce7e 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -4,4 +4,4 @@ option('poodle', type: 'boolean', value: true, description: 'Whether to apply th
 option('ref_tracking', type: 'boolean', value: false, description: 'Whether to use explicit reference 
tracking.')
 option('iso_639_xml', type: 'string', value: '', description: 'Full path to the ISO 639 XML file.')
 option('iso_3166_xml', type: 'string', value: '', description: 'Full path to the ISO 3166 XML file.')
-option('libunwind', type: 'feature', value: 'enabled', description: 'Whether to use libunwind.')
+option('libunwind', type: 'boolean', value: true, description: 'Whether to depend on libunwind.')