Auto-sync with upstream branch master
    
    Upstream commit: 37ac8e635a29810318f6d79902102e2e96b2b5bf
    
    - Add elision tunables.  Drop related configure flag.
    - Linux: Implement interfaces for memory protection keys
    - math: Add _Float64, _Float32x function aliases
    - math: Use sign as double for reduced case in sinf
    - math: fix sinf(NAN)
    - math: s_sinf.c: Replace floor with simple casts
    - et_EE locale: Base collation on iso14651_t1 (swbz#22517)
    - tr_TR locale: Base collation on iso14651_t1 (swbz#22527)
    - hr_HR locale: Avoid single code points for digraphs in LC_TIME (swbz#10580)
    - S390: Fix backtrace in vdso functions