Auto-sync with upstream branch master
    
    Upstream commit: 49c3c37651e2d2ec4ff8ce21252bbbc08a9d6639
    
    - Fix alignment bug in Safe-Linking
    - Typo fixes and CR cleanup in Safe-Linking
    - Use Linux 5.6 and GMP 6.2.0 in build-many-glibcs.py.
    - Add new file missed in previous hppa commit.
    - powerpc: Add support for fmaf128() in hardware
    - Fix data race in setting function descriptors during lazy binding on hppa.
    - sparc: Move __fenv_{ld,st}fsr to fenv-private.h
    - x86: Remove feraiseexcept optimization
    - math: Remove fenvinline.h
    - hurd: Make O_TRUNC update mtime/ctime
    - Add Safe-Linking to fastbins and tcache
    - Add benchtests for roundeven and roundevenf.
    - time: Add a __itimerval64 struct
    - time: Add a timeval with a 32-bit tv_sec and tv_usec
    - sysv/linux: Rename alpha functions to be alpha specific
    - ARC: add definitions to elf/elf.h
    - powerpc64: apply -mabi=ibmlongdouble to special files
    - powerpc64le: add -mno-gnu-attribute to *f128 objects and difftime
    - Makeconfig: sandwich gnulib-tests between libc/ld linking of tests
    - powerpc64le: Ensure correct ldouble compiler flags are used
    - Fix tests which expose ldbl -> _Float128 redirects
    - ldbl-128ibm-compat: PLT redirects for using ldbl redirects internally