feature: add buildmode=wasi-legacy to support existing base of users who expected the

older behavior for wasi modules to not return an exit code as if they were reactors.

See #4726 for some details on what this is intended to address.

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/runtime/runtime_wasmentry.go

@@ -52,6 +52,15 @@ func wasmEntryReactor() {
 	}
 }
 
+// This is the _start entry point, when using -buildmode=wasi-legacy.
+func wasmEntryLegacy() {
+	// These need to be initialized early so that the heap can be initialized.
+	initializeCalled = true
+	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
+	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
+	run()
+}
+
 // Whether the runtime was initialized by a call to _initialize or _start.
 var initializeCalled bool