GCC >= 8 - build failure

[dvershinin]

replace-filter-nginx-module-0.0.1/src/ngx_http_replace_script.c: In function 'ngx_http_replace_script_add_var_code':
replace-filter-nginx-module-0.0.1/src/ngx_http_replace_script.c:612:18: error: cast between incompatible function types from 'size_t (*)(ngx_http_replace_script_engine_t *)' {aka 'long unsigned int (*)(struct <anonymous> *)'} to 'void (*)(ngx_http_replace_script_engine_t *)' {aka 'void (*)(struct <anonymous> *)'} [-Werror=cast-function-type]
     code->code = (ngx_http_replace_script_code_pt)
                  ^
cc1: all warnings being treated as errors

[agentzh]

@dvershinin Thanks for the report! Mind to contribute a patch? It looks like an easy fix to just adjust the type declaration of void ....