bridge-utils: copy from oldpackages

* update Makefile accoring to CONTRIBUTING.md, set maintainer
* fix file offset handling
* use https://git.kernel.org/pub/scm/linux/kernel/git/shemminger/bridge-utils.git for source code

Signed-off-by: Nikolay Martynov <mar.kolya@gmail.com>

net/bridge-utils/patches/001-libbridge_cflags.patch

@@ -0,0 +1,11 @@
+--- a/libbridge/Makefile.in
++++ b/libbridge/Makefile.in
+@@ -5,7 +5,7 @@ AR=ar
+ RANLIB=@RANLIB@
+ 
+ CC=@CC@
+-CFLAGS = -Wall -g $(KERNEL_HEADERS)
++CFLAGS = -Wall -g @CFLAGS@ $(KERNEL_HEADERS)
+ 
+ prefix=@prefix@
+ exec_prefix=@exec_prefix@

net/bridge-utils/patches/010-fix_struct_in6_addr_usage.patch

@@ -0,0 +1,10 @@
+--- a/libbridge/libbridge.h
++++ b/libbridge/libbridge.h
+@@ -20,6 +20,7 @@
+ #define _LIBBRIDGE_H
+ 
+ #include <sys/socket.h>
++#include <netinet/in.h>
+ #include <linux/if.h>
+ #include <linux/if_bridge.h>
+