[seahorse] build: Don't build manpage by default

[Niels De Graef <nielsdg src gnome org>]

commit 45fb39d6210745296e17ee6dd11c0b25df708968
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Sun Mar 17 23:47:04 2019 +0100

    build: Don't build manpage by default
    
    This was failing the build on Continuous on a Sunday night, so let's
    just fix it like this.

 meson_options.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson_options.txt b/meson_options.txt
index 2b2ce4cf..a8ca960f 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -6,4 +6,4 @@ option('keyservers-support', type: 'boolean', value: true, description: 'Add sup
 option('hkp-support', type: 'boolean', value: true, description: 'Add support for keyservers using LDAP')
 option('ldap-support', type: 'boolean', value: true, description: 'Add support for keyservers using HKP')
 option('key-sharing', type: 'boolean', value: true, description: 'Add support for DNS-SD key sharing')
-option('manpage', type: 'boolean', value: true, description: 'Build and install the manpage')
+option('manpage', type: 'boolean', value: false, description: 'Build and install the manpage (requires 
xsltproc)')