Unused macro and variable removed.

The macro NGX_HTTP_DAV_COPY_BLOCK is not used since 8101d9101ed8 (0.8.9).
The variable ngx_accept_mutex_lock_file was never used.

src/event/ngx_event.c

diff --git a/src/event/ngx_event.c b/src/event/ngx_event.c
index c4c6120..e2857f0 100644
--- a/src/event/ngx_event.c
+++ b/src/event/ngx_event.c
@@ -56,7 +56,6 @@
 ngx_uint_t            ngx_accept_mutex_held;
 ngx_msec_t            ngx_accept_mutex_delay;
 ngx_int_t             ngx_accept_disabled;
-ngx_file_t            ngx_accept_mutex_lock_file;
 
 
 #if (NGX_STAT_STUB)

src/http/modules/ngx_http_dav_module.c

diff --git a/src/http/modules/ngx_http_dav_module.c b/src/http/modules/ngx_http_dav_module.c
index a97c60e..2a17992 100644
--- a/src/http/modules/ngx_http_dav_module.c
+++ b/src/http/modules/ngx_http_dav_module.c
@@ -10,8 +10,6 @@
 #include <ngx_http.h>
 
 
-#define NGX_HTTP_DAV_COPY_BLOCK      65536
-
 #define NGX_HTTP_DAV_OFF             2