C++ agent logging APIs

The agent framework provides four logging APIs (macros) for use in agent entry points written in C++.

These APIs include two application logging macros:

VCSAG_CONSOLE_LOG_MSG(sev, msgid, flags, fmt, variable_args...)
VCSAG_LOG_MSG(sev, msgid, flags, fmt, variable_args...)

and the macros for debugging:

VCSAG_LOGDBG_MSG(dbgsev, flags, fmt, variable_args...)
VCSAG_RES_LOG_MSG(dbgsev, flags, fmt, variable args...)