remove nightly features

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

crossbeam-fix-metadata.diff

@@ -0,0 +1,8 @@
+--- crossbeam-0.4.1/Cargo.toml	1970-01-01T01:00:00+01:00
++++ crossbeam-0.4.1/Cargo.toml	2018-09-08T23:41:51.896701+02:00
+@@ -38,5 +38,4 @@
+ 
+ [features]
+ default = ["use_std"]
+-nightly = ["crossbeam-epoch/nightly", "crossbeam-utils/nightly"]
+ use_std = ["crossbeam-epoch/use_std", "crossbeam-utils/use_std"]

rust-crossbeam.spec

@@ -13,6 +13,9 @@ Summary:        Support for concurrent programming
 License:        MIT or ASL 2.0
 URL:            https://crates.io/crates/crossbeam
 Source0:        https://crates.io/api/v1/crates/%{crate}/%{version}/download#/%{crate}-%{version}.crate
+# Initial patched metadata
+# * No nightly
+Patch0:         crossbeam-fix-metadata.diff
 
 ExclusiveArch:  %{rust_arches}