TT#111150 use intermediate variable for ftell()

This function returns -1 as error value, which would be lost if
immediately assigned to an unsigned type.

Change-Id: If9050b793519a529df671527c3a3e33ca2afc1bd

recording-daemon/db.c

@@ -385,14 +385,15 @@ void db_close_stream(output_t *op) {
 			return;
 		}
 		fseek(f, 0, SEEK_END);
-		stream.len = ftell(f);
-		if (stream.len < 0) {
+		long pos = ftell(f);
+		if (pos < 0) {
 			ilog(LOG_ERR, "Failed to get file position: %s", strerror(errno));
 			fclose(f);
 			if ((output_storage & OUTPUT_STORAGE_FILE))
 				goto file;
 			return;
 		}
+		stream.len = pos;
 		fseek(f, 0, SEEK_SET);
 		stream.s = malloc(stream.len);
 		if (stream.s) {