Strengthen Linux kernel capabilities detection

Strengthen Linux kernel capabilities detection

- Add `CONFIG_BLOCK` Linux config requirement to
  `ZFS_AC_KERNEL_CONFIG_DEFINED`. OpenZFS won't compile without
  that block device support due to large amount of functional
  dependencies on it.

- Remove dependency on `groups_alloc()` in
  `ZFS_AC_KERNEL_SRC_GROUP_INFO_GID` to circumvent the missing stub
  in Linux 4.X kernel headers.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #13351