Initial support for building for Windows with OpenWatcom

.github/workflows/os2.yml

@@ -1,22 +0,0 @@
-name: Build (OS/2)
-
-on: [push, pull_request]
-
-jobs:
-  os2:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: open-watcom/setup-watcom@v0
-      - name: Build SDL2
-        run: |
-          wmake -f Makefile.os2
-      - name: Build tests
-        run: |
-          cd test && wmake -f Makefile.os2
-          cd ..
-      - name: distclean
-        run: |
-          wmake -f Makefile.os2 distclean
-          cd test && wmake -f Makefile.os2 distclean
-          cd ..

.github/workflows/watcom.yml

@@ -0,0 +1,30 @@
+name: Build (OpenWatcom)
+
+on: [push, pull_request]
+
+jobs:
+  os2:
+    name: ${{ matrix.platform.name }}
+    runs-on: windows-latest
+
+    strategy:
+      matrix:
+        platform:
+        - { name: Windows, makefile: Makefile.w32 }
+        - { name: OS/2,    makefile: Makefile.os2 }
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: open-watcom/setup-watcom@v0
+      - name: Build SDL2
+        run: |
+          wmake -f ${{ matrix.platform.makefile }}
+      - name: Build tests
+        run: |
+          cd test && wmake -f ${{ matrix.platform.makefile }}
+          cd ..
+      - name: distclean
+        run: |
+          wmake -f ${{ matrix.platform.makefile }} distclean
+          cd test && wmake -f ${{ matrix.platform.makefile }} distclean
+          cd ..