Re-enabled silent rules, disabled by error in previous commit

configure.ac

@@ -28,7 +28,7 @@ AC_CONFIG_SRCDIR([src/modbus.c])
 AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([foreign])
 # enable nice build output on automake1.11
-#m4_ifdef([AM_SILENT_RULES],[AM_SILENT_RULES([yes])])
+m4_ifdef([AM_SILENT_RULES],[AM_SILENT_RULES([yes])])
 
 LIBMODBUS_VERSION_MAJOR=libmodbus_version_major
 LIBMODBUS_VERSION_MINOR=libmodbus_version_minor