ctf: rename identifiers ERROR and DEBUG_PROCESS

When trying to use src/cpp-common/bt2/trace-ir.hpp, the build fails on
Windows (MinGW64) with:

      CXX      viewer-connection.o
    In file included from /usr/x86_64-w64-mingw32/include/windows.h:71,
                     from /usr/x86_64-w64-mingw32/include/winsock2.h:23,
                     from /home/smarchi/src/babeltrace/src/compat/socket.h:15,
                     from /home/smarchi/src/babeltrace/src/plugins/ctf/lttng-live/viewer-connection.cpp:23:
    /home/smarchi/src/babeltrace/src/cpp-common/bt2/trace-ir.hpp:1081:9: error: expected identifier before numeric constant
     1081 |         ERROR = BT_EVENT_CLASS_LOG_LEVEL_ERROR,
          |         ^~~~~

This is because there is an "ERROR" macro defined in wingdi.h:

    https://github.com/mirror/mingw-w64/blob/7da5597116c5335e9a0f1154d171750bd2531baf/mingw-w64-headers/include/wingdi.h#L75

Same thing with DEBUG_PROCESS.  Rename to ERROR to ERR and DEBUG_PROCESS
to DEBUG_PROC.

Change-Id: I31ed7578e84ce1bee883f0d9f121c1ea47e8a679
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8368
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>