fixed compile error in gcc version 4.1.2

Hello.
I faced the problems while compiling this module with gcc version 4.1.2 and nginx-1.6.0.
And then i fixed codes. 

....
		-o objs/addon/ngx_kafka_module/ngx_http_kafka_module.o \
		/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c
cc1: warnings being treated as errors
/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c: In function ‘ngx_http_kafka_main_conf_broker_add’:
/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c:162: warning: value computed is not used
make[1]: *** [objs/addon/ngx_kafka_module/ngx_http_kafka_module.o] Error 1
make[1]: Leaving directory `/tmp/nginx/nginx-1.6.0'
make: *** [build] Error 2

....
make -f objs/Makefile
make[1]: Entering directory `/tmp/nginx/nginx-1.6.0'
cc -c -pipe  -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Werror -g -I/usr/local/include/hiredis/  -I src/core -I src/event -I src/event/modules -I src/os/unix -I objs -I src/http -I src/http/modules -I src/http/modules/perl -I src/mail \
		-o objs/addon/ngx_kafka_module/ngx_http_kafka_module.o \
		/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c
cc1: warnings being treated as errors
/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c: In function ‘ngx_http_kafka_post_callback_handler’:
/tmp/nginx/ngx_kafka_module/ngx_http_kafka_module.c:285: warning: ‘main_conf’ may be used uninitialized in this function
make[1]: *** [objs/addon/ngx_kafka_module/ngx_http_kafka_module.o] Error 1
make[1]: Leaving directory `/tmp/nginx/nginx-1.6.0'
make: *** [build] Error 2