optimize: resty.core.shdict: removed one unused top-level Lua variable.

Signed-off-by: Yichun Zhang (agentzh) <[email protected]>

Author: thibaultcha

lib/resty/core/shdict.lua

@@ -19,9 +19,6 @@ local ngx_shared = ngx.shared
 local getmetatable = getmetatable
 
 
-local MAX_ERR_MSG_LEN = 128
-
-
 ffi.cdef[[
     int ngx_http_lua_ffi_shdict_get(void *zone, const unsigned char *key,
         size_t key_len, int *value_type, unsigned char **str_value_buf,