Shorten some test names

Paths to object files generated from them were too long and caused errors

src/test/run-pass/specialization/defaultimpl/cross-crate-defaults.rs

@@ -8,13 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:specialization_cross_crate_defaults.rs
+// aux-build:cross_crate_defaults.rs
 
 #![feature(specialization)]
 
-extern crate specialization_cross_crate_defaults;
+extern crate cross_crate_defaults;
 
-use specialization_cross_crate_defaults::*;
+use cross_crate_defaults::*;
 
 struct LocalDefault;
 struct LocalOverride;

src/test/run-pass/specialization/defaultimpl/cross-crate-no-gate.rs

@@ -10,11 +10,11 @@
 
 // Test that specialization works even if only the upstream crate enables it
 
-// aux-build:specialization_cross_crate.rs
+// aux-build:cross_crate.rs
 
-extern crate specialization_cross_crate;
+extern crate cross_crate;
 
-use specialization_cross_crate::*;
+use cross_crate::*;
 
 fn  main() {
     assert!(0u8.foo() == "generic Clone");

src/test/run-pass/specialization/defaultimpl/cross-crate.rs

@@ -8,13 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:specialization_cross_crate.rs
+// aux-build:cross_crate.rs
 
 #![feature(specialization)]
 
-extern crate specialization_cross_crate;
+extern crate cross_crate;
 
-use specialization_cross_crate::*;
+use cross_crate::*;
 
 struct NotClone;