Print signal-exits from tests

src/dds/build/builder.cpp

     bool generate_catch2_main   = false;
 };
 
+void log_failure(const test_failure& fail) {
+    spdlog::error("Test '{}' failed! [exitted {}]", fail.executable_path.string(), fail.retc);
+    if (fail.signal) {
+        spdlog::error("Test execution received signal {}", fail.signal);
+    }
+    if (trim_view(fail.output).empty()) {
+        spdlog::error("(Test executable produced no output");
+    } else {
+        spdlog::error("Test output:\n{}[dds - test output end]", fail.output);
+    }
+}
+
 lm::library
 prepare_catch2_driver(test_lib test_driver, const build_params& params, build_env_ref env_) {
     fs::path test_include_root = params.out_root / "_catch-2.10.2";
     auto test_failures = plan.run_all_tests(env, params.parallel_jobs);
     spdlog::info("Test execution finished in {:n}ms", sw.elapsed_ms().count());
 
-    for (auto& failures : test_failures) {
-        spdlog::error("Test {} failed! Output:\n{}[dds - test output end]",
-                      failures.executable_path.string(),
-                      failures.output);
+    for (auto& fail : test_failures) {
+        log_failure(fail);
     }
     if (!test_failures.empty()) {
         throw_user_error<errc::test_failure>();

src/dds/build/plan/exe.cpp

         f.executable_path = exe_path;
         f.output          = res.output;
         f.retc            = res.retc;
+        f.signal          = res.signal;
         return f;
     }
 }

src/dds/build/plan/exe.hpp

     fs::path    executable_path;
     std::string output;
     int         retc;
+    int         signal;
 };
 
 /**