Learn the compiler and linker flags, by calling out into
a temporary Makefile that includes the Ocarina-generated one
(see instructions from Jerome in ticket 311)

But don't do this for RTEMS! Because for this to work, we
need to wait for access to the EnvVars information...
The Ocarina-generated makefile depends on proper setting
of RTEMS_MAKEFILE_PATH, which itself depends on the
deployment processor.