Auto-sync with upstream branch master
    
    Upstream commit: e9e7f24543e6d1b0a31641f144697e261df6ccd7
    
    - configure: Replace obsolete AC_TRY_LINK with AC_LINK_IFELSE
    - configure: Remove obsolete AC_CHECK_TOOL_PREFIX
    - configure: Replace obsoleted AC_HELP_STRING with AS_HELP_STRING
    - Update syscall lists for Linux 5.11.
    - Correct hppa EFD_NONBLOCK, IN_NONBLOCK, SFD_NONBLOCK and TFD_NONBLOCK defines.
    - string: Work around GCC PR 98512 in rawmemchr
    - tst: time: Provide Y2038 tests for mktime (tst-mktime4.c)
    - tst: Provide test for difftime
    - tst: Provide test for ctime
    - tst: Provide test for sched_rr_get_interval
    - S390: Add new hwcap values.
    - aarch64: Fix sys/ptrace.h if linux headers are included
    - elf: Do not copy vDSO soname when setting up link map
    - x86: Remove the extra space between "# endif"
    - hurd: Fix fstatfs build failure
    - linux: Remove stat-check.c
    - linux: Remove overflow.h
    - linux: Consolidate internal_statvfs
    - linux: Consolidate statvfs implementations
    - linux: Consolidate fstatvfs implementations
    - linux: Consolidate statfs implementations
    - linux: Consolidate fstatfs implementations
    - linux: Set LFS statfs as default
    - linux: Set default kernel_stat.h to LFS
    - linux: Fix STATFS_IS_STATFS64 definition