Unify svc_vc shared data handling.

This change both removes a trivial crash due to inconsistent
initialization of shared data, and while doing this, makes all
related code more uniform.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>
Fix a portability issue in svc_dg_recv().

Size of 'sa_family_t' data type differs across platforms (2 bytes on Linux
x86_64 vs 1 byte on amd64 FreeBSD). Assigning a value to a variable of data type
sa_family_t thus requires an explicit cast to avoid the strict compile errors.

Signed-off-by: Sachin Bhamare <sbhamare@panasas.com>