test: disable crashing tests on WASI

WASI doesn't support spawning a subprocess, so crash tests crashes the test harness itself. Those should be skipped until proper subprocess support is available.

Author: MaxDesiatov

test/Concurrency/Runtime/actor_assert_precondition_executor.swift

@@ -78,10 +78,12 @@ actor Someone {
         await MainFriend().callCheckMainActor()
       }
 
+      #if !os(WASI)
       tests.test("precondition on actor (main): wrongly assume the main executor, from actor on other executor") {
         expectCrashLater(withMessage: "Incorrect actor executor assumption; Expected 'MainActor' executor.")
         await Someone().callCheckMainActor()
       }
+      #endif
 
       // === Global actor -----------------------------------------------------
 
@@ -94,4 +96,4 @@ actor Someone {
 
     await runAllTestsAsync()
   }
-}
+}