[openwrt] update switch.[ch] for swconfig structs

Signed-off-by: Ion Dumitrache <gear@ines.ro>
switch Makefile+ initial rules for openwrt backend

Signed-off-by: Ion Dumitrache <gear@ines.ro>
switch.h: missing ;

Signed-off-by: Ion Dumitrache <gear@ines.ro>
[openwrt] Switch API functions, so far

issue #63
issue #64
issue #65
issue #66
issue #67
issue #68
issue #70
issue #71
issue #64

Signed-off-by: Ion Dumitrache <gear@ines.ro>
[openwrt] swlib helper functions, issue #94

Signed-off-by: Ion Dumitrache <gear@ines.ro>