[gnome-build-meta] Pin librsvg to version 2.42.3

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 68891a8612e35b8fbb2dc0a2b1d88eddc68eb38a
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sat Mar 10 12:06:14 2018 -0600

    Pin librsvg to version 2.42.3

 elements/core-deps/librsvg.bst | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/elements/core-deps/librsvg.bst b/elements/core-deps/librsvg.bst
index c63717e..670f0d0 100644
--- a/elements/core-deps/librsvg.bst
+++ b/elements/core-deps/librsvg.bst
@@ -1,8 +1,9 @@
 kind: autotools
+# FIXME: https://gitlab.gnome.org/GNOME/librsvg/issues/226
 sources:
-- kind: git
-  url: git_gnome_org:librsvg
-  track: master
+- url: https://download.gnome.org/sources/librsvg/2.42/librsvg-2.42.3.tar.xz
+  kind: tar
+  ref: 704f2c44b9b170fc5498de36a161d01ca8f584ba9c42654b98565a7b7bcbe657
 depends:
 - core-deps/gdk-pixbuf.bst
 - core-deps/glib.bst