Fixes #503, fixes #507:

* No longer using anything from the `helper_string.h` header we had lifted from the CUDA samples' common includes directory
* Refactored `simpleStreams.cu` to run with all possible synch policies (thus foregoing the need for a command-line argument; and - we were ignoring the other one, -anyway)

examples/common.hpp

@@ -202,10 +202,16 @@ cuda::device::id_t choose_device(int argc, char const** argv)
 	}
 
 	cuda::device::id_t device_id { -1 };
-	// Being very cavalier about our command-line arguments here...
-	if (std::strncmp(argv[1],"--device=", std::strlen("--device=")) == 0) {
-		auto actual_arg = argv[1] + std::strlen("--device=");
-		device_id = (argc > 1) ? std::stoi(actual_arg) : cuda::device::default_device_id;
+	if (argc == 1) {
+		device_id = cuda::device::default_device_id;
+	}
+	else {
+		std::string device_id_arg { argv[1] };
+		std::string prefix { "--device=" };
+		if (device_id_arg.rfind(prefix) == 0) {
+			device_id_arg = device_id_arg.substr(prefix.length());
+		}
+		device_id = std::stoi(device_id_arg);
 	}
 
 	if (device_id < 0) {