Support local .a, skip if unable to find .a

ci/test-cuda.sh

@@ -2,11 +2,17 @@
 
 cd "$(dirname "$0")/.."
 
-: "${libcuda_verify_ed25519_URL:?environment variable undefined}"
+LIB=libcuda_verify_ed25519.a
+if [[ ! -r $LIB ]]; then
+  if [[ -z "${libcuda_verify_ed25519_URL:-}" ]]; then
+    echo "$0 skipped.  Unable to locate $LIB"
+    exit 0
+  fi
 
-export LD_LIBRARY_PATH=/usr/local/cuda/lib64
-export PATH=$PATH:/usr/local/cuda/bin
-curl -X GET -o libcuda_verify_ed25519.a "$libcuda_verify_ed25519_URL"
+  export LD_LIBRARY_PATH=/usr/local/cuda/lib64
+  export PATH=$PATH:/usr/local/cuda/bin
+  curl -X GET -o $LIB "$libcuda_verify_ed25519_URL"
+fi
 
 # shellcheck disable=SC1090    # <-- shellcheck can't follow ~
 source ~/.cargo/env