Fix testing of features at the workspace level

The test.sh script contains logic to avoid testing features that don't
exist in the subcrates, but this logic breaks apart when run from the
top level.  Fix this by always running with the requested features at
the top level.

test.sh

@@ -46,7 +46,7 @@ run_tests() {
                 info "Testing ${dir} with default features"
                 cargo test ${cargo_args} -- --include-ignored ${test_args}
             else
-                if grep -q "^{feature} = \[" Cargo.toml; then
+                if [ "${dir}" = . ] || grep -q "^{feature} = \[" Cargo.toml; then
                     info "Testing ${dir} with feature=${feature}"
                     cargo test --features="${feature}" ${cargo_args} -- --include-ignored ${test_args}
                 else