refactor(c/libuv): general fixes & optimize code

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): optimize functions

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): mv name

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): modify libs

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): use new buffer arg

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv/demo): optimize code style with go style

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): optimize code and add comment

Signed-off-by: hackerchai <i@hackerchai.com>

fix(c/libuv): fix TranslateSysError

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): remove go wrapper

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv/demo): refactor c style

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/liobuv/demo): Some adjustments after removing go wrapper

refactor(c/libuv/demo): add print in echo_server

Signed-off-by: hackerchai <i@hackerchai.com>

doc(c/libuv): add README.md for c/libuv

Signed-off-by: hackerchai <i@hackerchai.com>

feat(c/libuv): implement poll_init_socket

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(c/libuv): mv poll_init_socket function

Signed-off-by: hackerchai <i@hackerchai.com>

refactor(demo): remove libuv demo

Signed-off-by: hackerchai <i@hackerchai.com>

c/libuv/README.md

@@ -0,0 +1,44 @@
+LLGo wrapper of libuv
+=====
+
+## How to install
+
+### on macOS (Homebrew)
+
+```sh
+brew install libuv
+```
+
+### on Linux (Debian/Ubuntu)
+
+```sh
+apt-get install -y libuv1-dev
+```
+
+### on Linux (CentOS/RHEL)
+
+```sh
+yum install -y libuv-devel
+```
+
+### on Linux (Arch Linux)
+
+```sh
+pacman -S libuv
+```
+
+## Demos
+
+The `_demo` directory contains our demos (it start with `_` to prevent the `go` command from compiling it):
+
+* [async_fs](_demo/async_fs/async_fs.go): a simple async file read demo
+* [echo_server](_demo/echo_server/echo_server.go): a basic async tcp echo server
+
+### How to run demos
+
+To run the demos in directory `_demo`:
+
+```sh
+cd <demo-directory>  # eg. cd _demo/sqlitedemo
+llgo run .
+```