This is by no means perfect, but it gets the kernel tasks running on my
machine out of the profiles. We will no doubt need to add more in the
future, or find a way to record a flag for that in the capture format.
If we get an empty string, just normalize that to NULL so that we can be
more likely to match equality checks via hash comparison.
Additionally, break hashes out into two so that we can improve the
situation where some symbols do not have paths but still match. This
can happen with bundled symbols.
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).
