const char *fmt in ngx_conf_log_error()

src/core/ngx_conf_file.c

diff --git a/src/core/ngx_conf_file.c b/src/core/ngx_conf_file.c
index c48d814..6d5f510 100644
--- a/src/core/ngx_conf_file.c
+++ b/src/core/ngx_conf_file.c
@@ -1006,7 +1006,7 @@
 
 void ngx_cdecl
 ngx_conf_log_error(ngx_uint_t level, ngx_conf_t *cf, ngx_err_t err,
-    char *fmt, ...)
+    const char *fmt, ...)
 {
     u_char   errstr[NGX_MAX_CONF_ERRSTR], *p, *last;
     va_list  args;

src/core/ngx_conf_file.h

diff --git a/src/core/ngx_conf_file.h b/src/core/ngx_conf_file.h
index 763de44..86c60a4 100644
--- a/src/core/ngx_conf_file.h
+++ b/src/core/ngx_conf_file.h
@@ -322,7 +322,7 @@
     ngx_uint_t conf_prefix);
 ngx_open_file_t *ngx_conf_open_file(ngx_cycle_t *cycle, ngx_str_t *name);
 void ngx_cdecl ngx_conf_log_error(ngx_uint_t level, ngx_conf_t *cf,
-    ngx_err_t err, char *fmt, ...);
+    ngx_err_t err, const char *fmt, ...);
 
 
 char *ngx_conf_set_flag_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);