[libsoup] meson: Fix introspection variable

[Iñigo Martínez <inigomartinez src gnome org>]

commit 3ac2959b76d1d18cc4453f2af4fdc00df19d9e6b
Author: Iñigo Martínez <inigomartinez gmail com>
Date:   Fri Apr 13 16:12:41 2018 +0200

    meson: Fix introspection variable
    
    When VAPI support is enabled, meson checks that introspection is
    enabled. This is done by checking `enable_gir` variable. However,
    introspection support is set in the `enable_introspection`
    variable.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=795233

 meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index ed9e082..1f34362 100644
--- a/meson.build
+++ b/meson.build
@@ -229,7 +229,7 @@ endif
 ############
 enable_vapi = get_option('vapi')
 if enable_vapi
-  assert(enable_gir, 'vapi support was requested, but introspection support is mandatory.')
+  assert(enable_introspection, 'vapi support was requested, but introspection support is mandatory.')
   assert(add_languages('vala', required: false), 'vapi support was requested, but vala not found.')
 endif