demo/cgofull: add multi cgo module and macro calling

_demo/cgofull/pymod1/pymod1.go

@@ -0,0 +1,11 @@
+package pymod1
+
+/*
+#cgo pkg-config: python3-embed
+#include <Python.h>
+*/
+import "C"
+
+func Float(f float64) *C.PyObject {
+	return C.PyFloat_FromDouble(C.double(f))
+}