The AM_SILENT_RULES macro needs an argument to be enabled. Currently, if the silent-rules option is set in AM_INIT_AUTOMAKE, the action is an AC_REQUIRE on the macro, which runs it without any arg, resulting in an useless action.
The only way for now to enable silent-rules is to call AM_SILENT_RULES([yes]), the silent-rules option has no effect at all. This patch solves it, calling the macro with the right arg