Fix multi line handling for compat check results

Fix multi line handling for compat check results

When a multi line result is submitted via the command pipe, any multi line
output is escaped to a actual string '\n', because any external command only
can be a single line.

Example:
  [1432735140] PROCESS_SERVICE_CHECK_RESULT;host;service;3;Test1\nTest2|test=1

We need to unescape this values, just like we use to escape multi line output
for IDO and status.dat.

fixes #9324

Signed-off-by: Michael Friedrich <michael.friedrich@netways.de>