LCL: Minor clean-up of code in lcl-fpgui. Issue #24166, patch from Graeme

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40665 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL: Adds TProgressBar support for lcl-fpgui. Issue #24167, patch from Graeme

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40666 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL: Simplifies the setup to compile lcl-fpgui. Issue #24168, patch from Graeme

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40667 4005530d-fff6-0310-9dd1-cebe43e6787f