build: avoid expansion of commented macros
build: avoid expansion of commented macros

'#' does not ignore the line at the m4 level, "dnl" does.

Signed-off-by: Jan Engelhardt <f383ed465f890d2e8ea864dd0c28cf8ec50a8942@inai.de>
Signed-off-by: Marc Kleine-Budde <4a0ea1158d3cc63151119c05b1bff00c0bdbf421@pengutronix.de>

lalten/libsocketcan,lalten/libsocketcan,lalten/libsocketcan