* Split linux and windows build of lifemngr to be able to build
them independently.
* Install life_mngr.service
* Avoid the following Makefile error output by explicitly checking
Windows cross compiler availability:
make[4]: x86_64-w64-mingw32-gcc: Command not found
make[4]: [Makefile:47: all-win] Error 127 (ignored)
Tracked-On: #5660
Signed-off-by: Helmut Buchsbaum <helmut.buchsbaum@opensource.tttech-industrial.com>