[fractal] Add rustc version restriction

[Alexandre Franke <afranke src gnome org>]

commit 275b811497880fa1d1ecc6fbbde436f6f0ff89c8
Author: Alejandro Domínguez <adomu net-c com>
Date:   Sun Oct 18 15:11:21 2020 +0200

    Add rustc version restriction

 meson.build | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/meson.build b/meson.build
index fb9e380e..e518b815 100644
--- a/meson.build
+++ b/meson.build
@@ -31,6 +31,10 @@ cargo = find_program('cargo', required: true)
 gresource = find_program('glib-compile-resources', required: true)
 gschemas = find_program('glib-compile-schemas', required: true)
 
+rust_version = meson.get_compiler('rust').version()
+min_req_rust_version = '1.46.0'
+assert(rust_version >= min_req_rust_version, 'Minimum rust version ' + min_req_rust_version)
+
 if get_option('profile') == 'development'
   profile = 'Devel'
   name_suffix = ' (Development)'