[glib/meson-wrapfile-use-libffi-tarball] meson: switch the libffi wrap file to the last release supporting meson 0.47

[Christoph Reiter <creiter src gnome org>]

commit 0b328d38792ed4b2f0bd0a38968ec9a23dd7e0b5
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Mon Nov 26 17:34:32 2018 +0100

    meson: switch the libffi wrap file to the last release supporting meson 0.47
    
    So we don't require a newer meson than for glib itself. See !471

 subprojects/libffi.wrap | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/subprojects/libffi.wrap b/subprojects/libffi.wrap
index 3d15e2a8a..2b05f0976 100644
--- a/subprojects/libffi.wrap
+++ b/subprojects/libffi.wrap
@@ -1,4 +1,4 @@
-[wrap-git]
+[wrap-file]
 directory=libffi
-url=https://github.com/centricular/libffi.git
-revision=meson
+source_url = https://github.com/centricular/libffi/archive/3.2.9999.tar.gz
+source_filename = libffi-meson-3.2.9999.tar.gz