gitian: Use split-debug.sh for Win builds

Debug splitting was first introduced in 7e7eb2724, then gitian-linux.yml
changed to using split-debug.sh in 9d2536208. Here we change
gitian-win.yml to use split-debug.sh as well.

contrib/gitian-descriptors/gitian-win.yml

@@ -164,8 +164,8 @@ script: |
     find . -name "lib*.la" -delete
     find . -name "lib*.a" -delete
     rm -rf ${DISTNAME}/lib/pkgconfig
-    find ${DISTNAME}/bin -type f -executable -exec ${i}-objcopy --only-keep-debug {} {}.dbg \; -exec ${i}-strip -s {} \; -exec ${i}-objcopy --add-gnu-debuglink={}.dbg {} \;
-    find ${DISTNAME}/lib -type f -exec ${i}-objcopy --only-keep-debug {} {}.dbg \; -exec ${i}-strip -s {} \; -exec ${i}-objcopy --add-gnu-debuglink={}.dbg {} \;
+    find ${DISTNAME}/bin -type f -executable -print0 | xargs -0 -n1 -I{} ../contrib/devtools/split-debug.sh {} {} {}.dbg
+    find ${DISTNAME}/lib -type f -print0 | xargs -0 -n1 -I{} ../contrib/devtools/split-debug.sh {} {} {}.dbg
     find ${DISTNAME} -not -name "*.dbg"  -type f | sort | zip -X@ ${OUTDIR}/${DISTNAME}-${i}.zip
     find ${DISTNAME} -name "*.dbg"  -type f | sort | zip -X@ ${OUTDIR}/${DISTNAME}-${i}-debug.zip
     cd ../../