fsmonitor: avoid socket location check if using hook

fsmonitor: avoid socket location check if using hook

If monitoring is done via fsmonitor hook rather than IPC there is no
need to check if the location of the Unix Domain socket (UDS) file is
on a remote filesystem.

Signed-off-by: Eric DeCosta <edecosta@mathworks.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>