Remove hard coded sysroot paths from Coin

If sysroot is updated, the paths change and the current Coin implementation doesn't work. Instead we should remove the hard coded paths from Coin. One solution is to provision them as prefixed env variables that Coin takes into use when needed. E.g. QNX_PATH is prepended to PATH when QNX is built.

If sysroot provides a script that sets all the env variables, then we have an option of sourcing that one when needed. This however depends on that script not to be renamed or moved. This script is however is something that could be provisioned to an ENV variable. That way we don't need to hard code its name either.