ci.sh: Add x86_64 win cross build.

Signed-off-by: Jeff Epler <jepler@gmail.com>

.github/workflows/ports_windows.yml

@@ -140,7 +140,7 @@ jobs:
       working-directory: tests
       run: python run-tests.py --print-failures
 
-  cross-build-on-linux:
+  cross-build-i386-win-on-linux:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
@@ -148,3 +148,12 @@ jobs:
       run: source tools/ci.sh && ci_windows_setup
     - name: Build
       run: source tools/ci.sh && ci_windows_build
+
+  cross-build-x86_64-win-on-linux:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install packages
+      run: source tools/ci.sh && ci_windows_setup
+    - name: Build
+      run: source tools/ci.sh && ci_windows64_build

ports/windows/variants/standard/mpconfigvariant.mk

@@ -1 +1,6 @@
 # This is the default variant when you `make` the Windows port.
+
+ifneq ($(DISABLE_PLUGIN),1)
+# Enable format string checking
+include $(TOP)/py/fmtplugin.mk
+endif

tools/ci.sh

@@ -877,6 +877,12 @@ function ci_windows_build {
     make ${MAKEOPTS} -C ports/windows submodules
     make ${MAKEOPTS} -C ports/windows CROSS_COMPILE=i686-w64-mingw32-
 }
+function ci_windows64_build {
+    make ${MAKEOPTS} -C mpy-cross
+    make ${MAKEOPTS} -C ports/windows submodules
+    make ${MAKEOPTS} -C ports/windows CROSS_COMPILE=x86_64-w64-mingw32-
+}
+
 
 ########################################################################################
 # ports/zephyr