fix msvc build failure introduced by previous commit

src/http/ngx_http_special_response.c

diff --git a/src/http/ngx_http_special_response.c b/src/http/ngx_http_special_response.c
index 8ddfce9..d249c27 100644
--- a/src/http/ngx_http_special_response.c
+++ b/src/http/ngx_http_special_response.c
@@ -299,7 +299,7 @@
 };
 
 
-static ngx_str_t  ngx_http_get_name = { 3, "GET " };
+static ngx_str_t  ngx_http_get_name = { 3, (u_char *) "GET " };
 
 
 ngx_int_t