[PATCH] Improve LinuxThreads compatibility in rfork()

[Petr Salinger]

> Below is the patch I intend to commit after you retest it.

I applied it against our 8.2 based package,
altered our "clone" to use this new 
interface and run eglibc testsuite. No regression.

Our runtime detection of this new interface will be based
on "sysctl kern.osreldate".


> some rewording to the manual page.

You might want to reword also RFLINUXTHPN part
"kernel will return" -> "kernel will deliver"

Can we expect MFC before 8.3 release ?

Thanks

 	Petr