*: let libfmt quote strings

src/input/plugins/AlsaInputPlugin.cxx

@@ -256,13 +256,13 @@ AlsaInputStream::Recover(int err)
 	switch(err) {
 	case -EPIPE:
 		FmtDebug(alsa_input_domain,
-			 "Overrun on ALSA capture device \"{}\"",
+			 "Overrun on ALSA capture device {:?}",
 			 device);
 		break;
 
 	case -ESTRPIPE:
 		FmtDebug(alsa_input_domain,
-			 "ALSA capture device \"{}\" was suspended",
+			 "ALSA capture device {:?} was suspended",
 			 device);
 		break;
 	}

src/input/plugins/ArchiveInputPlugin.cxx

@@ -28,7 +28,7 @@ OpenArchiveInputStream(Path path, Mutex &mutex)
 		}
 	} catch (...) {
 		FmtDebug(input_domain,
-			 "not an archive, lookup '{}' failed: {}",
+			 "not an archive, lookup {:?} failed: {}",
 			 path, std::current_exception());
 		return nullptr;
 	}