cgo: add support for #cgo noescape lines

Here is the proposal:
https://github.com/golang/go/issues/56378

They are documented here:
https://pkg.go.dev/cmd/cgo@master#hdr-Optimizing_calls_of_C_code

This would have been very useful to fix
https://github.com/tinygo-org/bluetooth/issues/176 in a nice way. That
bug is now fixed in a different way using a wrapper function, but once
this new noescape pragma gets included in TinyGo we could remove the
workaround and use `#cgo noescape` instead.

cgo/testdata/errors.go

@@ -10,6 +10,11 @@ typedef struct {
 
 typedef someType noType; // undefined type
 
+// Some invalid noescape lines
+#cgo noescape
+#cgo noescape foo bar
+#cgo noescape unusedFunction
+
 #define SOME_CONST_1 5) // invalid const syntax
 #define SOME_CONST_2 6) // const not used (so no error)
 #define SOME_CONST_3 1234 // const too large for byte