Merge pull request #2 from haonan3344/patch-1

In windows cannot "go get ...",for  "undefined reference to libiconv"

converter.go

@@ -2,6 +2,9 @@ package iconv
 
 /*
 #cgo darwin LDFLAGS: -liconv 
+#cgo freebsd LDFLAGS: -liconv
+#cgo linux LDFLAGS: -liconv
+#cgo windows LDFLAGS: -liconv
 #include <stdlib.h>
 #include <iconv.h>
 */