RTDM: More IOCTL requests to be handled in primary mode

Xenomai 2 to 3 migration says "RTDM drivers implementing differentiated ioctl() support for both domains should serve all real-time only requests from ioctl_rt(), returning -ENOSYS for any unrecognized request, which will cause the adaptive switch to take place automatically to the ioctl_nrt() handler. The ioctl_nrt() should then implement all requests which may be valid from the regular Linux domain exclusively."

Cosmetic change : rtdm_in_rt_context instead of ipipe_root_p.

Xenomai won't merge .nrt ops delegation to rtdm task through rtpc. Moved it to rtdmnet.c.

Fixed wrong xeno_lib_ldflags, missing --posix --auto-init-solib

More hgignore

This fix a segfault in xenomai_posix example when calling pthread_setschedparam(cyclic_thread, ...) from main thread. As a side effect EL2004 becomes EL2088 - that's what IU have for testing.

More check in rtdm mmap, also use kernel memory instead of virtual memory.

Use new RTDM's mmap, not anymore a special case compared to normal linux mmap.

Fixed rtdmnet.c PFX and removed useless commented code.

rtdmnet module should follow same (un)loading rules as generic module

Added devices/rtdmnet.c, heavily based on devices/generic.c, and with similar purpose. It uses Xenomai's RTNet/RTDM socket instead of Linux socket.

Fix C/C++ linking problem in tool/ethercat

Continued update of master's rtdm part to xenomai 3 : ioctl context now obtained from rtdm_fd

Continued update of master's rtdm part to xenomai 3 : rtdm_user_info_t now replaced by rtdm_fd

migrate posix xenomai example to Xenomai3

migrate native xenomai example to Xenomai3

rt_dev_* has been abandonned in Xenomai3, on user side we use the regular POSIX I/O calls exposed by libcobalt

rtdm skin is equivalent to posix in Xenomai3's xeno-config. Replace XENOMAI_RTDM_*FLAGS by XENOMAI_LIB_*FLAGS to distinguish lib/example flags.

Add module installation path to configure options

Intermediate state while updating master's RTDM part to Xenomai 3

Added --with-xenomai-config to override xenomai config command, also allowing special environment variables to be passed.

Example : --with-xenomai-config="DESTDIR=/path/to/staging /path/to/xeno-config"

Fixed scheduler settings in dc_user example; use CLOCK_MONOTONIC.

Use sched_setscheduler() to set priority in user example.

Applied 0002-use-setup_timer-for-v4.15.patch from Beckhoff.

Applied CCAT patch 0001-fix-ccat-netdev-for-v4.11.patch from Beckhoff.

Ignore missing SDO entries in output.

Improved buffer overflow messages.

Support scheduler parameters in kernels >= 4.11.

Added missing configure options to documentation.