BUILD: fcgi-app: include proxy.h in fcgi-app.c

It's needed for proxies_list and used to be inherited via cfgparse.h.
diff --git a/src/fcgi-app.c b/src/fcgi-app.c
index 6dca3ec..f33650f 100644
--- a/src/fcgi-app.c
+++ b/src/fcgi-app.c
@@ -20,7 +20,7 @@
 #include <haproxy/http_fetch.h>
 #include <haproxy/http_htx.h>
 #include <haproxy/log.h>
-#include <haproxy/proxy-t.h>
+#include <haproxy/proxy.h>
 #include <haproxy/regex.h>
 #include <haproxy/sample.h>
 #include <haproxy/server-t.h>