Bug#947759: Configuration optimizations for the cloud variant

[Josh Triplett <josh@joshtriplett.org>]

Following up on this, here's a simplified list of optimizations for the
cloud variant in one place, taking into account the previous reply.
Would it help to get this in the form of a patch or MR on
https://salsa.debian.org/kernel-team/linux/ ?

- Please compile in the NVME driver and the EXT4 filesystem; this will
  allow many cloud systems to avoid using an initramfs at all, which
  substantially improves boot time.

- Please consider changing the default kernel compression to LZ4, which
  decompresses much faster and thus boots faster. (Benchmarks to support
  this: https://smackerelofopinion.blogspot.com/2019/09/ ) Please
  consider doing this on the non-cloud configuration as well.

- Please disable CONFIG_ACPI_BGRT; a cloud kernel doesn't need to spend
  time or code space looking for a boot logo that won't exist.

- Please disable the CONFIG_CPU_SUP_* options for CPUs that no cloud
  provider uses (concretely, please disable everything except
  CONFIG_CPU_SUP_AMD and CONFIG_CPU_SUP_INTEL).

- Please disable CONFIG_GNSS_*, which won't be hooked up to a cloud
  server.

- Please disable CONFIG_GTP for the same reason.

- Please configure CONFIG_INPUT_MOUSEDEV as a module, not built-in, as
  most cloud servers won't have a mouse and probing for one takes time.

- Please change CONFIG_NET_MPLS_GSO from y to m. While nothing will
  automatically load it, it's sufficiently rare that loading it manually
  seems reasonable, and this would reduce attack surface and boot time.

- Please disable CONFIG_NUMA_EMU, only used to create fake-NUMA systems
  for debugging.

- Please disable CONFIG_PCIPCWATCHDOG and CONFIG_RMI4_*, which won't
  appear on a cloud server.

- Please enable CONFIG_SCHED_MC_PRIO (on both cloud and non-cloud
  kernels).

- Please disable CONFIG_VFIO_PCI_VGA and CONFIG_VGA_SWITCHEROO, which
  won't appear on cloud.

Thank you,
Josh Triplett