Disable x86 error code bitwise enum in default build

Only generate the bitwise enumerations when
CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM is enabled, so the default build
does not generate traces which lead to warnings when viewed with
babeltrace 1.x and babeltrace 2 with default options.

commit 8c7f2a9f2732b11f5cc9798cecb621420cc0e972
Author: Francis Deslauriers <francis.deslauriers@efficios.com>
Date:   Fri Jun 5 18:42:54 2020 -0400

    x86: add error code enum to pagefault tracepoints

Change-Id: I7901fad216b4774a9bbf3665568f357321805871
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>