[jhbuild] defaults: Drop -Dgtk_doc=false which is fatal if unknown/invalid in newer meson

[Rico Tzschichholz <ricotz src gnome org>]

commit 624bcf68591aaa17d9f6119c8b9672b92ac6120c
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Jun 20 08:11:39 2018 +0200

    defaults: Drop -Dgtk_doc=false which is fatal if unknown/invalid in newer meson

 jhbuild/defaults.jhbuildrc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/jhbuild/defaults.jhbuildrc b/jhbuild/defaults.jhbuildrc
index ca56e046..bb211464 100644
--- a/jhbuild/defaults.jhbuildrc
+++ b/jhbuild/defaults.jhbuildrc
@@ -78,7 +78,7 @@ except ImportError as _e:
 # override environment variables, command line arguments, etc
 autogenargs = '--disable-static --disable-gtk-doc'
 cmakeargs = ''
-mesonargs = '--buildtype=debugoptimized -Dgtk_doc=false'
+mesonargs = '--buildtype=debugoptimized'
 makeargs = ''
 ninjaargs = ''
 cflags = ''