compiler, runtime: enable go:wasmexport for wasip2 (#4499)

* compiler: prefer go:wasmexport over go:export

* runtime, targets/wasip2: enable -buildmode=c-shared for wasip2

* runtime: rename import from wasi_run to wasiclirun (PR feedback)

src/runtime/runtime_wasip2.go

@@ -6,18 +6,19 @@ import (
 	"unsafe"
 
 	"internal/wasi/cli/v0.2.0/environment"
+	wasiclirun "internal/wasi/cli/v0.2.0/run"
 	monotonicclock "internal/wasi/clocks/v0.2.0/monotonic-clock"
+
+	"internal/cm"
 )
 
 type timeUnit int64
 
-//export wasi:cli/run@0.2.0#run
-func __wasi_cli_run_run() uint32 {
-	// These need to be initialized early so that the heap can be initialized.
-	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
-	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
-	run()
-	return 0
+func init() {
+	wasiclirun.Exports.Run = func() cm.BoolResult {
+		callMain()
+		return false
+	}
 }
 
 var args []string
@@ -51,3 +52,6 @@ func sleepTicks(d timeUnit) {
 func ticks() timeUnit {
 	return timeUnit(monotonicclock.Now())
 }
+
+func beforeExit() {
+}

src/runtime/runtime_wasmentry.go

@@ -1,4 +1,4 @@
-//go:build tinygo.wasm && !wasip2 && !js
+//go:build tinygo.wasm && !js
 
 package runtime