compiler: conform to latest iteration of wasm types proposal (#4501)

compiler: align with current wasm types proposal

https://github.com/golang/go/issues/66984

- Remove int and uint as allowed types in params, results, pointers, or struct fields
- Only allow small integers in pointers, arrays, or struct fields
- enforce structs.HostLayout usage per wasm types proposal
https://github.com/golang/go/issues/66984
- require go1.23 for structs.HostLayout
- use an interface to check if GoVersion() exists
This permits TinyGo to compile with Go 1.21.
- use goenv.Compare instead of WantGoVersion
- testdata/wasmexport: use int32 instead of int
- compiler/testdata: add structs.HostLayout
- compiler/testdata: improve tests for structs.HostLayout

testdata/wasmexport-noscheduler.go

@@ -18,16 +18,16 @@ func hello() {
 }
 
 //go:wasmexport add
-func add(a, b int) int {
+func add(a, b int32) int32 {
 	println("called add:", a, b)
 	return a + b
 }
 
 //go:wasmimport tester callOutside
-func callOutside(a, b int) int
+func callOutside(a, b int32) int32
 
 //go:wasmexport reentrantCall
-func reentrantCall(a, b int) int {
+func reentrantCall(a, b int32) int32 {
 	println("reentrantCall:", a, b)
 	result := callOutside(a, b)
 	println("reentrantCall result:", result)

testdata/wasmexport.go

@@ -21,15 +21,15 @@ func hello() {
 }
 
 //go:wasmexport add
-func add(a, b int) int {
+func add(a, b int32) int32 {
 	println("called add:", a, b)
 	addInputs <- a
 	addInputs <- b
 	return <-addOutput
 }
 
-var addInputs = make(chan int)
-var addOutput = make(chan int)
+var addInputs = make(chan int32)
+var addOutput = make(chan int32)
 
 func adder() {
 	for {
@@ -41,10 +41,10 @@ func adder() {
 }
 
 //go:wasmimport tester callOutside
-func callOutside(a, b int) int
+func callOutside(a, b int32) int32
 
 //go:wasmexport reentrantCall
-func reentrantCall(a, b int) int {
+func reentrantCall(a, b int32) int32 {
 	println("reentrantCall:", a, b)
 	result := callOutside(a, b)
 	println("reentrantCall result:", result)