Clean up sources (remove temporary hack)

Remove the temporary hack added so these could build before
O_CLOFORK (etc) became visible to userland.

NFCI.

Libc functions which need to know about O_CLOFORK.

These are Ricardo Branco's libc updates for affected functions
that use O_CLOFORK &/or FD_CLOFORK.

These are currently padded (by me) with temporary additions so
they build while the O_CLOFORK/FD_CLOFORK definitions remain hidden
to userland.

branches: 1.2.2;
finish renaming __dup3110 to __dup3100

version dup3