r=dbragg, sr=mscott, a=asa
For the nsIProcess component, which is only used by XPInstall, instead of calling
nspr for process creation, we call a simplified version which, on windows, will
cause the child process not to inherit fds open by the forking process.
Fix is only XP_WIN. nspr will provide a more risky, non-nsIProcess, XP solution at
some point which is either achieved by modifying open() to accept a non-inherit
flag (on win32) or do an fcntl() on Unix (see the bug for details specific to the
fcntl()), or provide another pair of create processes functions that are geared
towards non-inheriting process creation.
The bug fixed here is the XP installer is not able, on win32, to remove the
components.reg file from the "cleanup" process, which leads to all sorts of mayhem,
because the cleanup process inherits the component.reg fd which is open at the
time the cleanup process is forked, and this it cannot remove something it has an
open reference to.
