Rollup merge of #90569 - wesleywiser:fix_only_i686_tests, r=Mark-Simulacrum

Fix tests using `only-i686` to use the correct `only-x86` directive

We translate `i686` to `x86` which means tests marked as `only-i686`
never ran. Update those tests to use `only-x86`.

We parse the `only-` architecture directive here

27143a9094/src/tools/compiletest/src/util.rs (L160-L168)

and we translate `i686` to `x86` here

27143a9094/src/tools/compiletest/src/util.rs (L56)

src/test/ui/extern/extern-methods.rs

@@ -1,5 +1,5 @@
 // run-pass
-// only-i686
+// only-x86
 
 trait A {
     extern "fastcall" fn test1(i: i32);

src/test/ui/extern/extern-thiscall.rs

@@ -1,5 +1,5 @@
 // run-pass
-// only-i686
+// only-x86
 
 #![feature(abi_thiscall)]
 

src/test/ui/extern/extern-vectorcall.rs

@@ -1,7 +1,7 @@
 // run-pass
 // revisions: x64 x32
 // [x64]only-x86_64
-// [x32]only-i686
+// [x32]only-x86
 
 #![feature(abi_vectorcall)]