Certain backends do network scans even if the 'local_only'
parameter for 'sane_get_devices()' is true. Fix that.
Changes:
1. Modify 'sanei_configure_attach()' so that backend specific
data may be passed to the 'attach()' function.
2. Use this in certain backends to pass the value of the
'local_only' parameter so that network related activities
are only carried out when the value is false.
Traced source of conflicting connect() defines to p5
backend including libc.h header file. On OSX, this
includes socket.h. Since backend didn't really need
libc.h header and is not a networked backend, reverted
last fix and implement header based fix.
Signed-off-by: Chris Bagwell <chris@cnpbagwell.com>