Bundle GCC runtime in Win32 bin package

After discussing with some Windows user, this actually seems to be
a common thing to do (it seemed weird to me, but I know Windows' handling
of DLLs is weird anyways), so bundle that runtime and reinstate the
full test run for Win32.

.github/workflows/testing.yml

@@ -77,6 +77,7 @@ jobs:
           mv rgbgfx bins/rgbgfx.exe
           cp /usr/${{ matrix.triplet }}/lib/zlib1.dll bins
           cp /usr/${{ matrix.triplet }}/bin/libpng16-16.dll bins
+          if [ ${{ matrix.bits }} -eq 32 ]; then cp /usr/lib/gcc/${{ matrix.triplet }}/7.3-win32/libgcc_s_sjlj-1.dll bins; fi
       - name: Upload Windows binaries
         uses: actions/upload-artifact@v1
         with:
@@ -88,11 +89,6 @@ jobs:
     strategy:
       matrix:
         bits: [32, 64]
-        include:
-          - bits: 32
-            rgbgfx_fail: true
-          - bits: 64
-            rgbgfx_fail: false
     runs-on: windows-2019
     steps:
       - uses: actions/checkout@v2
@@ -109,14 +105,3 @@ jobs:
         shell: bash
         run: |
           test/run-tests.sh
-        if: matrix.rgbgfx_fail == false
-      - name: Run tests (without RGBGFX)
-        shell: bash
-        run: |
-          pushd test/asm
-          ./test.sh
-          popd
-          pushd test/link
-          ./test.sh
-          popd
-        if: matrix.rgbgfx_fail == true