Auto-sync with upstream branch master
    
    Upstream commit: 48c3c1238925410b4e777dc94e2fde4cc9132d44
    
    - Linux: Fix __glibc_has_include use for <sys/stat.h> and statx (#1721129)
    - <sys/cdefs.h>: Inhibit macro expansion for __glibc_has_include
    - Add IPV6_ROUTER_ALERT_ISOLATE from Linux 5.1 to bits/in.h
    - aarch64: handle STO_AARCH64_VARIANT_PCS
    - aarch64: add STO_AARCH64_VARIANT_PCS and DT_AARCH64_VARIANT_PCS
    - powerpc: Remove optimized finite
    - math: Use wordsize-64 version for finite
    - powerpc: Remove optimized isinf
    - math: Use wordsize-64 version for isinf
    - powerpc: Remove optimized isnan
    - math: Use wordsize-64 version for isnan
    - benchtests: Add isnan/isinf/isfinite benchmark
    - powerpc: copysign cleanup
    - powerpc: consolidate rint
    - libio: freopen of default streams crashes in old programs (swbz#24632)
    - Linux: Deprecate <sys/sysctl.h> and sysctl
    - <sys/stat.h>: Use Linux UAPI header for statx if available and useful
      (#1721129)
    - <sys/cdefs.h>: Add __glibc_has_include macro
    - Improve performance of memmem
    - Improve performance of strstr
    - Benchmark strstr hard needles
    - Fix malloc tests build with GCC 10