Test XRay only for supported targets

Now that the compiler accepts "-Z instrument-xray" option only when
targeting one of the supported targets, make sure to not run the
codegen tests where the compiler will fail.

Like with other compiletests, we don't have access to internals,
so simply hardcode a list of supported architectures here.

tests/codegen/instrument-xray/basic.rs

@@ -1,5 +1,6 @@
 // Checks that `-Z instrument-xray` produces expected instrumentation.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=always
 
 #![crate_type = "lib"]

tests/codegen/instrument-xray/options-combine.rs

@@ -1,5 +1,6 @@
 // Checks that `-Z instrument-xray` options can be specified multiple times.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=skip-exit
 // compile-flags: -Z instrument-xray=instruction-threshold=123
 // compile-flags: -Z instrument-xray=instruction-threshold=456

tests/codegen/instrument-xray/options-override.rs

@@ -1,5 +1,6 @@
 // Checks that the last `-Z instrument-xray` option wins.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=always
 // compile-flags: -Z instrument-xray=never
 

tests/ui/instrument-xray/flags-always-never-1.rs

@@ -1,5 +1,6 @@
 // Checks that `-Z instrument-xray` does not allow `always` and `never` simultaneously.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=always,never
 // error-pattern: incorrect value `always,never` for unstable option `instrument-xray`
 

tests/ui/instrument-xray/flags-always-never-2.rs

@@ -1,6 +1,7 @@
 // Checks that `-Z instrument-xray` allows `always` and `never` sequentially.
 // (The last specified setting wins, like `-Z instrument-xray=no` as well.)
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=always
 // compile-flags: -Z instrument-xray=never
 // check-pass

tests/ui/instrument-xray/flags-basic.rs

@@ -1,5 +1,6 @@
 // Verifies basic `-Z instrument-xray` flags.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray
 // compile-flags: -Z instrument-xray=skip-exit
 // compile-flags: -Z instrument-xray=ignore-loops,instruction-threshold=300

tests/ui/instrument-xray/flags-dupe-always.rs

@@ -1,5 +1,6 @@
 // Checks that `-Z instrument-xray` does not allow duplicates.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=always,always
 // error-pattern: incorrect value `always,always` for unstable option `instrument-xray`
 

tests/ui/instrument-xray/flags-dupe-ignore-loops.rs

@@ -1,5 +1,6 @@
 // Checks that `-Z instrument-xray` does not allow duplicates.
 //
+// needs-xray
 // compile-flags: -Z instrument-xray=ignore-loops,ignore-loops
 // error-pattern: incorrect value `ignore-loops,ignore-loops` for unstable option `instrument-xray`