Fixed excessive memory usage while parsing configuration.

The b->pos points to the next symbol here.

Reported by ilexshen.

src/core/ngx_conf_file.c

diff --git a/src/core/ngx_conf_file.c b/src/core/ngx_conf_file.c
index ec3c1fa..8273a7f 100644
--- a/src/core/ngx_conf_file.c
+++ b/src/core/ngx_conf_file.c
@@ -680,7 +680,7 @@
                     return NGX_ERROR;
                 }
 
-                word->data = ngx_pnalloc(cf->pool, b->pos - start + 1);
+                word->data = ngx_pnalloc(cf->pool, b->pos - 1 - start + 1);
                 if (word->data == NULL) {
                     return NGX_ERROR;
                 }