omcproxy: fix compilation on little-endian CPUs

omcproxy: fix compilation on little-endian CPUs

Don't use cpu_to_be32 outside of a function.

In file included from /omcproxy-2017-02-14-1fe6f48f/src/omcproxy.h:51:0,
                 from omcproxy-2017-02-14-1fe6f48f/src/mrib.c:39:
omcproxy-2017-02-14-1fe6f48f/src/mrib.c:57:34: error: braced-group within expression allowed only inside a function
 static uint32_t ipv4_rtr_alert = cpu_to_be32(0x94040000);
                                  ^
cc1: warning: unrecognized command line option '-Wno-gnu'

Ref: https://downloads.openwrt.org/releases/faillogs-18.06/arm_cortex-a9_vfpv3/base/omcproxy/compile.txt
Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>
[more verbose commit message]
Signed-off-by: Petr Štetiar <ynezz@true.cz>
(cherry picked from commit cb4d00d1841ef6269114f2bd3880800dbdfba3b1)