Golang生成共享库(shared library)以及Golang生成C可调用的动态库.so和静态库.a

Golang类似于C的静态语言，效率也接近于C，如果Golang也可以导出可供C调用的库，那可以和很多高级语言say goodbye了，goodbye似乎又有点武断，但至少说，Golang可以做很多事，而且效率优于很多高级语言，这样说应该没有问题。
接下来，就从三个方面分别来介绍Golang中关于库的使用。

##Using Share Library

The latest Go 1.5 version is out. As part of the new features, Go compiler can compile packages as a shared libraries.

It accepts -buildmode argument that determines how a package is compiled. These are the following options:

* archive: Build the listed non-main packages into .a files. Packages named main are ignored.
* c-archive: Build the listed main package, plus all packages it imports, into a C archive file.
* c-shared: Build the listed main packages, plus all packages that they import, into C shared libraries.
* shared: Combine all the listed non-main packages into a single shared library.
* exe: Build the listed main packages and everything they import into executables. Packages not named main are ignored.
By default, listed main packages are built into executables and liste