windows build: update build command for latest miqt

Makefile

@@ -57,9 +57,12 @@ build/qbolt-${VERSION}-debian12-x86_64.tar.xz: build/qbolt
 # Windows release (docker)
 
 build/qbolt.exe: $(SOURCES)
-	( $(DOCKER) image ls | fgrep qbolt-win64-cross ) || ( cd docker && $(DOCKER) build -t qbolt-win64-cross:latest -f win64-cross.Dockerfile . )
-	$(DOCKER) run --rm -v $(CURDIR):/qbolt -w /qbolt qbolt-win64-cross:latest /bin/sh -c "go build $(GOFLAGS_W) -o build/qbolt.exe"
-	upx --force build/qbolt.exe
+	# -flto causes internal compiler error
+	$(DOCKER) run --rm --id $$(id -u):$$(id -g) -v $(CURDIR):/src -w /src miqt/winqt6static:latest /bin/sh -c "CGO_CFLAGS='-Os -ffunction-sections -fdata-sections' CGO_CXXFLAGS='-Os -ffunction-sections -fdata-sections' CGO_LDFLAGS='-Wl,--gc-sections -fwhole-program' go build $(GOFLAGS_W) -o build/qbolt.exe"
+	# Must be stripped before upx'ing - @ref https://github.com/msys2/MSYS2-packages/issues/454
+	# However this removes the rsrc, loses the icon and causes a Defender detection
+	# strip build/qbolt.exe
+	# upx build/qbolt.exe
 
 build/qbolt-${VERSION}-windows-x86_64.zip: build/qbolt.exe
 	zip -9 -j build/qbolt-${VERSION}-windows-x86_64.zip build/qbolt.exe

docker/win64-cross.Dockerfile

@@ -1,20 +0,0 @@
-FROM golang:1.23-bookworm
-
-RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
-    apt-get install -qyy gnupg2 ca-certificates
-    
-RUN DEBIAN_FRONTEND=noninteractive \
-    echo "deb https://pkg.mxe.cc/repos/apt buster main" >/etc/apt/sources.list.d/mxeapt.list && \
-    apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 86B72ED9 && \
-    apt-get update && \
-    apt-get install -qyy mxe-x86-64-w64-mingw32.static-qt5 && \
-    apt-get clean
-
-ENV PATH=/usr/lib/mxe/usr/bin:$PATH
-
-ENV CXX=x86_64-w64-mingw32.static-g++
-ENV CC=x86_64-w64-mingw32.static-gcc
-ENV PKG_CONFIG=x86_64-w64-mingw32.static-pkg-config
-ENV GOOS=windows
-ENV CGO_ENABLED=1
-