Install more deps

.gitea/workflows/ci.yaml

@@ -43,11 +43,16 @@ jobs:
       # the per-job token is enough for a one-shot fetch.
       GITHUB_TOKEN: ${{ github.token }}
     steps:
-      - name: Install Go and curl
+      - name: Install Go and toolchain
         run: |
           set -eu
-          if ! command -v curl >/dev/null 2>&1; then
-            apk add --no-cache curl
+          # curl: fetch the Go tarball.
+          # build-base (gcc + musl-dev + make): `go test -race` requires cgo.
+          missing=""
+          command -v curl >/dev/null 2>&1 || missing="$missing curl"
+          command -v gcc  >/dev/null 2>&1 || missing="$missing build-base"
+          if [ -n "$missing" ]; then
+            apk add --no-cache $missing
           fi
           want="go${GO_VERSION}"
           have="$(/usr/local/go/bin/go env GOVERSION 2>/dev/null || echo none)"
@@ -62,6 +67,8 @@ jobs:
           fi
           echo "/usr/local/go/bin" >> "$GITHUB_PATH"
           echo "$HOME/go/bin" >> "$GITHUB_PATH"
+          # cgo on for the rest of the job (race detector needs it).
+          echo "CGO_ENABLED=1" >> "$GITHUB_ENV"
 
       - name: Checkout
         run: |