Auto-sync with upstream branch master
    
    Upstream commit: 076f09afbac1aa57756faa7a8feadb7936a724e4
    
    - Linux: Remove <sys/sysctl.h> and the sysctl function
    - posix: Add wait4 test case
    - linux: wait4: Fix incorrect return value comparison
    - hurd: add mach_print function
    - x32: Properly pass long to syscall [BZ #25810]
    - Add GRND_INSECURE from Linux 5.6 to sys/random.h
    - Update kernel version to 5.6 in tst-mman-consts.py.