In the interactive mode, inform users of different sample types
if the profile includes zero samples for selected sample type
by default (or through user-provided sample_index flag value).

The example output may look like

$ pprof mem.prof
Type: inuse_space
Time: Mar 20, 2018 at 11:36am (EDT)

No samples were found with the default sample value type.
Try "sample_index" command to analyze different sample values.

Entering interactive mode (type "help" for commands, "o" for options)
(pprof)

Update golang/go#24443