Auto-sync with upstream branch release/2.30/master
    
    Upstream commit: 994e529a37953a057b9e6c80afa03b03fd3724f2
    
    - Remove incorrect alloc_size attribute from pvalloc (swbz#25401)
    - login: Use pread64 in utmp implementation
    - Add nocancel version of pread64()
    - login: Introduce matches_last_entry to utmp processing
    - login: Acquire write lock early in pututline (swbz#24882)
    - login: Add nonstring attributes to struct utmp, struct utmpx (swbz#24899)
    - login: Remove double-assignment of fl.l_whence in try_file_lock
    - login: pututxline could fail to overwrite existing entries (swbz#24902)
    - login: Use struct flock64 in utmp (swbz#24880)
    - login: Disarm timer after utmp lock acquisition (swbz#24879)
    - login: Fix updwtmp, updwtmx unlocking
    - login: Replace macro-based control flow with function calls in utmp
    - login: Assume that _HAVE_UT_* constants are true
    - login: Remove utmp backend jump tables (swbz#23518)
    - misc/test-errno-linux: Handle EINVAL from quotactl
    - <string.h>: Define __CORRECT_ISO_CPP_STRING_H_PROTO for Clang (swbz#25232)
    - x86: Assume --enable-cet if GCC defaults to CET (swbz#25225)
    - libio: Disable vtable validation for pre-2.1 interposed handles (swbz#25203)
    - S390: Fix handling of needles crossing a page in strstr z15 ifunc-variant. (swbz#25226)
    - rtld: Check __libc_enable_secure before honoring LD_PREFER_MAP_32BIT_EXEC
      (CVE-2019-19126) (#1774682)
    - Don't use a custom wrapper macro around __has_include (swbz#25189)