Eliminate libqrexec-utils

[DemiMarie]

How to file a helpful issue

The problem you're addressing (if any)

libqrexec-utils is a shared library, creating compatibility requirements that make qrexec harder to improve. However, it should have no users outside of Qubes OS itself.

The solution you'd like

Replace it with a static library linked in qrexec-client, qrexec-daemon, qrexec-agent, qrexec-client-vm, and qrexec-fork-server. The first two can be replace by a single multi-call binary, as can the last three. Therefore, there will be no increase in code size.

The value to a user, and who that user might be

Developers will be able to ship new features more easily.

Completion criteria checklist

• Convert qrexec-client and qrexec-daemon into multi-call binary.
• Convert qrexec-agent, qrexec-fork-server, and qrexec-client-vm into multi-call binary.
• Link libqrexec-utils statically instead of dynamically.
• Stop shipping libqrexec-utils or libqrexec-utils.h (but keep shipping qrexec.h, as that’s the protocol definition).