compatibility:
- added linux unshare syscall
-- exp10 function
+- exp10/pow10 function
- sqrtl support on arm (previously missing)
- removed minimal linux/*.h headers that could conflict with real ones
- support for _LARGEFILE64_SOURCE (mapped to standard fcns with #define)
- better c89 compatibility in headers
- stub versions of sched_* functions (previously missing)
- pthread stacks no longer executable (compat with hardened kernels)
+- new ar.h and lastlog.h (legacy junk)
+- various other header improvements
optimization:
- additional x86_64 math asm