Fix: Useless exception print on user-cancellation. Add a missing cancellation point

src/dds/build/plan/compile_exec.cpp

         update_deps_info(neo::into(env.db), info);
     }
 
+    cancellation_point();
     // Return whether or not there were any failures.
     return okay;
 }

src/dds/util/parallel.cpp

 #include "./parallel.hpp"
 
+#include <dds/util/signal.hpp>
+
 #include <dds/util/log.hpp>
 
 using namespace dds;
 void dds::log_exception(std::exception_ptr eptr) noexcept {
     try {
         std::rethrow_exception(eptr);
+    } catch (const dds::user_cancelled&) {
+        // Don't log this one. The user knows what they did
     } catch (const std::exception& e) {
         dds_log(error, "{}", e.what());
     }