Move w64devkit.ini to the root to mirror "installs"

One of my goals is that the distribution can be re-built in place using
only Docker or Podman, and so the unpacked distribution mirrors the
repository layout. That hasn't been true for w64devkit.ini, which is the
only file interfering with this trick, so fix it.

Dockerfile

@@ -479,7 +479,7 @@ RUN sed -i s/CommCtrl/commctrl/ $(grep -Rl CommCtrl CPP/) \
 
 WORKDIR /
 RUN rm -rf $PREFIX/share/man/ $PREFIX/share/info/ $PREFIX/share/gcc-*
-COPY README.md Dockerfile src/w64devkit.ini $PREFIX/
+COPY README.md Dockerfile w64devkit.ini $PREFIX/
 RUN printf "id ICON \"$PREFIX/src/w64devkit.ico\"" >w64devkit.rc \
  && $ARCH-windres -o w64devkit.o w64devkit.rc \
  && $ARCH-gcc -DVERSION=$VERSION -nostdlib -fno-asynchronous-unwind-tables \