add cmake test build

.builds/cmake-alpine-edge.yml

@@ -0,0 +1,17 @@
+image: alpine/edge
+packages:
+  - build-base
+  - cmake
+  - kyua
+  - atf
+sources:
+  - https://git.sr.ht/~kaniini/pkgconf
+tasks:
+  - configure: |
+      mkdir -p ~/pkgconf/build
+      cd ~/pkgconf/build
+      cmake ~/pkgconf
+  - distcheck: |
+      cd ~/pkgconf/build
+      make
+      make test