Description of problem:
GD2 fails to open the server xlator to read its options. This causes GD2 to fail to start.

The reason for this is because, server xlator uses two external function from glusterfsd, glusterfs_mgmt_pmap_signout and glusterfs_autoscale_threads. These functions are not resolved when dlopen tries to load the xlator, causing it to fail with 'undefined symbol' error.

This is not a problem with normal brick operation, as the server xlator is loaded by glusterfsd, which already has the relevant symbols defined.


Version-Release number of selected component (if applicable):
4.0.0rc1

How reproducible:
Reproducible on packaged RPMs of GlusterFS-v4.0.0rc1 on Fedora and GlusterD2-v4.0.0rc1 always.

Steps to Reproduce:
1. On Fedora 27, install GlusterFS-v4.0.0rc1 from [1] and GlusterD2-v4.0.0rc1
2. Start glusterd2.

Actual results:

GD2 fails to start with logged error,
```
FATA[2018-02-28 15:02:53.345686] Failed to load xlator options                 error="dlopen(/usr/lib64/glusterfs/4.0.0rc1/xlator/protocol/server.so) failed; dlerror = /usr/lib64/glusterfs/4.0.0rc1/xlator/protocol/server.so: undefined symbol: glusterfs_mgmt_pmap_signout" source="[main.go:79:main.main]"
```


Expected results:
GD2 should not fail to start.

Additional info: