(cherry picked from commit 8aa86b5a)

(cherry picked from commit 7d8d21d815e6a99ba5959d28b7d59c69d034e8c3)

Allow to build on Mac OS.

Will use Darwin linker args if we have a Darwin platform.

Some platforms doesn't have iconv_open().

Anyway if http is not allowed, apache will redirect to https.

Assume there is iproutes redirection from port 80/443 to port defined in instance (so public port is 80/443).
Frontend has to be reachable from defaults ports, otherwise it has no sense.

Reverts the effects of 8dba9b27 but keep cleanup

Correct default software_type to RootSoftwareInstance.
Was: RootInstanceSoftware.

LAMP instances will request frontend instances but will still publish backend URL if frontend is not available.

Request has to fail if a connection parameter can not be accessed.
(cherry picked from commit 59fbe2ad)