extend findPerfDataFiles() to find perf data files

[GitMensch]

This came up in #677 which created the function (which is also to be used in #678)

Please let it:

• return all files per our file open - re

  hotspot/src/mainwindow.cpp

  Lines 287 to 294 in e6ce4c4

  	QString MainWindow::queryOpenDataFile()
  	{
  	const auto filter = tr("Hotspot data Files (perf*.data perf.data.* *.perfparser *.perfparser.*);;"
  	"Linux Perf Files (perf*.data perf.data.*);;"
  	"Perfparser Files (*.perfparser *.perfparser.*);;"
  	"All Files (*)");
  	return QFileDialog::getOpenFileName(this, tr("Open File"), QDir::currentPath(), filter);
  	}

  -> list dir for perf*.data perf.data.* *.perfparser *.perfparser.*
• order by date descending
• add an optional parameter to limit the result (this would be used with "1" in the existing cases and early exit the loop that gathers the files)