TEMP enable tail calls by default

prtest:full

crates/wasmtime/src/config.rs

@@ -214,7 +214,7 @@ impl Config {
 
         // This is on-by-default in `wasmparser` since it's a stage 4+ proposal
         // but it's not implemented in Wasmtime yet so disable it.
-        ret.features.tail_call = false;
+        ret.wasm_tail_call(true); // TEMP FITZGEN
 
         ret
     }
@@ -1598,6 +1598,11 @@ impl Config {
         let host = target_lexicon::Triple::host();
         let target = self.compiler_config.target.as_ref().unwrap_or(&host);
 
+        // TEMP FITZGEN
+        if target.architecture == Architecture::S390x {
+            self.wasm_tail_call(false);
+        }
+
         // On supported targets, we enable stack probing by default.
         // This is required on Windows because of the way Windows
         // commits its stacks, but it's also a good idea on other