tracewrap-2.0-rc2: fix zero width error (#9)

Sometimes protobuf calls us with a request to write an element of zero
size. The check will fail in this case.

tracewrap-2.0-rc1

fix issues with BFD arches (#7)

It came out that BFD architectures in `qemu/dis/bfd.h` folder is 9 years older,
than architectures in the `bap-frames/libtrace`, and the latter is 14
years older than the latest BFD release. In fact, the BFD architectures
are not stable, and numbers for them are allocated at each configuration
and depends on the configuration options. The choice to rely on them was
a bad decision. The better approach would be to use our own wired format
for arches, specified in protobuf or something like this. But so far,
we're relying on piqi, that doesn't have (a) normal enums with fixed
values, (b) normal extension mechanism. So we will still rely on the old
way of specifying architectures.

Now we will use architectures from `frames/libtrace/` library, to
ensure, that everyone has the same constants. To reduce confusion with
BFD we've moved all definitions to the `frames` namespace (i.e.,
`s/bfd_/frames_`).

This PR also fixes numerous issues with the build system:

1. protobuf now is built as a part of `all` target, no need to
   do `make -C protobuf`
2. protobuf will generate `librotoframes` library, instead of libtrace
   that nameclashed with at least two libraries: trace library from the
   qemu itself and libtrace from the bap-frames
3. configure script will properly expand paths
4. protobuf target will now depend on the `piqi` file in the frames
   library and if the latter is changed, the library will be regenerated
   and recompiled, as well as all dependencies.

v2.0.0-tracewrap-alpha

Merge pull request #5 from BinaryAnalysisPlatform/frames-2.0

This PR introduces Frames-2.0 protocol