libglusterfs: Use strncpy() instead of strcpy()

Use secure strncpy() to copy the input data to static buffer
and make sure to NULL terminate the copied buffer (if source
buffer is longer than static buffer).

Change-Id: If3564f1398c8eb92669d4bc92700bbdf6ee2278e
BUG: 1097417
Signed-off-by: Santosh Kumar Pradhan <spradhan@redhat.com>
Reviewed-on: http://review.gluster.org/7759
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Reviewed-by: Anand Avati <avati@redhat.com>
Tested-by: Anand Avati <avati@redhat.com>