Added RTS hooks for the timer manager.
setNumCapabilities calls GHC.Conc.IO.ioManagerCapabilitiesChanged before returning.

This enables the IO manager to change the number of IO loops it uses (usually one per capability).
Changed ioManagerCapabilitiesChanged to take no arguments.

ioManagerCapabilitiesChanged now queries getNumCapabilities for the current number of enabled capabilities.
Adding missing symbol in rts/package.conf.in.
Merge the new parallel I/O manager