Auto-sync with upstream branch master
    
    Upstream commit: 243b63337c2c02f30ec3a988ecc44bc0f6ffa0ad
    
    - libio: Free backup area when it not required (swbz#22415)
    - math: Fix nextafter and nexttoward declaration (swbz#22593)
    - math: New generic cosf
    - powerpc: POWER8 memcpy optimization for cached memory
    - x86-64: Add sinf with FMA
    - x86-64: Remove sysdeps/x86_64/fpu/s_sinf.S
    - math: Fix ctanh (0 + i NaN), ctanh (0 + i Inf) (swbz#22568)
    - lt_LT locale: Base collation on copy "iso14651_t1" (swbz#22524)
    - math: Add _Float32 function aliases
    - math: Make cacosh (0 + iNaN) return NaN + i pi/2 (swbz#22561)
    - hsb_DE locale: Base collation on copy "iso14651_t1" (swbz#22515)