Merge changes Ife4692e4,I7304cc1d,If19653d0,I769ca792,I93625d19, ...

* changes:
  Move <sys/sysconf.h> to <bits/sysconf.h>.
  Remove mbstowcs from <wchar.h>.
  Extract getopt and friends to <bits/getopt.h>
  Remove declaration of unlinkat from <fcntl.h>.
  Extract ioctl to <bits/ioctl.h>.
  Extract fcntl to <bits/fcntl.h>.
  Extract strcasecmp and friends to <bits/strcasecmp.h>.
  Make <bits/lockf.h> compile standalone.
  Make <android/dlext.h> compile standalone.
  Make the network headers compile standalone.
  Remove duplicate declaration of mlock, munlock.