mingw: Don't use deltarpm reconstruction.

The fedora docker images ship without the necessary metadata
to reconstruct rpm packages from installed data, so attempting
to download delta rpm packages when updating the system just
wastes time and bandwidth.

mingw/Dockerfile

@@ -2,7 +2,7 @@ FROM fedora:24
 MAINTAINER opus@xiph.org
 
 # Linux build.
-RUN dnf update -y
+RUN dnf update -y --setopt=deltarpm=0
 RUN dnf install -y git gcc make wget xz
 RUN dnf install -y autoconf automake libtool pkgconfig