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/symbols.go

@@ -9,6 +9,10 @@ static void staticfunc(int x);
 
 // Global variable signatures.
 extern int someValue;
+
+void notEscapingFunction(int *a);
+
+#cgo noescape notEscapingFunction
 */
 import "C"
 
@@ -18,6 +22,7 @@ func accessFunctions() {
 	C.variadic0()
 	C.variadic2(3, 5)
 	C.staticfunc(3)
+	C.notEscapingFunction(nil)
 }
 
 func accessGlobals() {