Auto-sync with upstream branch release/2.26/master
    
    Upstream commit: df8c219cb987cfe85c550efa693a1383a11e38aa
    
    - CVE-2017-17426: malloc: Fix integer overflow in tcache (swbz#22375)
    - CVE-2017-15804: glob: Fix overflow in GLOB_TILDE unescaping (swbz#22332)
    - malloc: Add single-threaded path to _int_malloc
    - powerpc: Update AT_HWCAP2 bits
    - malloc: Abort on heap corruption, without a backtrace (swbz#21754)
    - Don't use IFUNC resolver for longjmp or system in libpthread (swbz#21041)
    - powerpc: Replace lxvd2x/stxvd2x with lvx/stvx in P7's memcpy/memmove