DNM opal_info: print a component even when it does not contain any parameters

[ghost]

An attempt to 'fix' #1396. To test, I disabled all tcp btl parameter registration. Sure enough, ompi_info skips over the tcp btl in opal_info_show_mca_group_params(). With this patch, the parameter output is sectioned based on components. If a component does not contain any parameters, an empty section is displayed. Sample output below:

            MCA btl : ---------------------------------------------------
            MCA btl : parameter "btl" (current value: "", data source:
                      default, level: 2 user/detail, type: string)
                      Default selection set of components for the btl
                      framework (<none> means use all components that can
                      be found)
        MCA btl base: ---------------------------------------------------
        MCA btl base: parameter "btl_base_verbose" (current value:
                      "error", data source: default, level: 8 dev/detail,
                      type: int)
                      Verbosity level for the btl framework (default: 0)
                      Valid values: -1:"none", 0:"error", 10:"component",
                      20:"warn", 40:"info", 60:"trace", 80:"debug",
                      100:"max", 0 - 100
        MCA btl base: parameter "btl_base_include" (current value: "",
                      data source: default, level: 9 dev/all, type:
                      string)
        MCA btl base: parameter "btl_base_exclude" (current value: "",
                      data source: default, level: 9 dev/all, type:
                      string)
        MCA btl base: parameter "btl_base_warn_component_unused" (current
                      value: "1", data source: default, level: 9 dev/all,
                      type: int)
                      This parameter is used to turn on warning messages
                      when certain NICs are not used
         MCA btl tcp: ---------------------------------------------------

Note that despite the tcp btl not having any registered parameters, it still does show up in the listing. I've no idea if this even comes close to what @hppritcha had in mind 😄 We could drop the "------------------" from the output, for example.

[jsquyres]

@hjelmn Got any thoughts on how to have disabled components show up in ompi_info output?

[ghost]

Actually I think disabled components will still show up in opal_info_show_mca_group_params(). There appears to be a 'requested' flag which is used in asprintf() to potentially mark a component as "disabled".

Here, in the case of the modified tcp btl, the component is enabled but has not registered any parameters. The default ompi_info command only outputs parameters, so there would be no mention of the tcp btl.

At least such is my limited understanding of this code path :)

[hjelmn]

I think we created #1396 because it doesn't make sense to suppress printing the component list as part of ompi_info -a. Currently the list is only printed if -a is not specified.

[ghost]

Ah, so perhaps via opal_info_show_component_version() as is done when no command line parameters are passed to ompi_info?

[ghost]

Set this to DoNotMerge. I think I can do better...