[$] The first part of the 7.4 merge window

Since the merge window for 7.4 opened, there have been 6,753 non-mergechangesets pulled into the mainline repository. Many more are expected,especially given the possibility that this merge window will be extended tothree weeks. Still, even this initial set brought in a number of new features,in addition to the continued general cleanups and security fixes that the kernelhas seen recently.