Fixed off-by-one error in shared zone initialization.

On systems without atomic ops, not enough space was allocated
for mutex's file name during shared zone initialization.

src/core/ngx_cycle.c

diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index f3ac24d..083c764 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -921,7 +921,8 @@
 
 #else
 
-    file = ngx_pnalloc(cycle->pool, cycle->lock_file.len + zn->shm.name.len);
+    file = ngx_pnalloc(cycle->pool,
+                       cycle->lock_file.len + zn->shm.name.len + 1);
     if (file == NULL) {
         return NGX_ERROR;
     }