[$] 5.12 Merge window, part 1

The beginning of the 5.12 merge window was delayed as the result of severeweather in the US Pacific Northwest. Once Linus Torvalds got going, though, hewasted little time; as of this writing, just over 8,600 non-mergechangesets have been pulled into the mainline repository for the 5.12release - over a period of about two days. As one might imagine, that workcontains a long list of significant changes.