It isn't valid to start with quote character ' for flag -ldflags.
Go cmd older than 1.19 just ignores the error. Starting from go 1.19,
Go cmd will fail with error message something like below,
```
stderr: invalid value "'-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'" for flag -ldflags: parameter may not start with quote character '
```
Actually we don't have such quote character ' when building
etcd/etcdctl/etcdutl.
Signed-off-by: Benjamin Wang <wachao@vmware.com>
The current Makefile doesn't allow the compilation of the tools directory.
This commit creates a build library file, updates the Makefile
and a top level script fod building tools.
To build the tools, you can run make build_tools.
As before, you can run make build to build etcd binaries.
