Use std::dec to print the begin_timestamp

Change-Id: I88377b840b2e2cce278575bc398cbdc296e6dfd7


[ROCm/roctracer commit: 753d543022]

projects/roctracer/plugin/file/file.cpp

@@ -238,7 +238,7 @@ class file_plugin_t {
 
     roctracer_timestamp_t app_begin_timestamp;
     CHECK_ROCTRACER(roctracer_get_timestamp(&app_begin_timestamp));
-    begin_ts << app_begin_timestamp << std::endl;
+    begin_ts << std::dec << app_begin_timestamp << std::endl;
     if (begin_ts.fail()) {
       warning("Cannot write to '%s'\n", begin_ts.path().c_str());
       return;