This shouldn't affect categorizing because that only uses the value if
is_toplevel. But with this added, we can use the count for weights in
other tooling w/o needing augmentation.
I don't want this to overlap with augmentation data, or be augmentation
data specific, so just keep our own private copy of this data in the
node to do the sort of things we want with it (such as summaries).
This brings together the two libraries back into one now that the whole
design is pretty well sorted out. They depend on roughly the same libraries
anyway and it's way easier of the single library can both read and write
the capture files (along with bringing in libsysprof-capture symbols in
a single place).
