LCL: Implement CharUpperBuff function. Issue #24493, patch from Stephano

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42580 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL: Fix accent chars in GTK2. Remove Gtk2LatinAccents define after testing. Issues #24750 and #22507. Original patch from Éderson Cássio

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42581 4005530d-fff6-0310-9dd1-cebe43e6787f
OpenGLControl: Implement release context method. Issue #24925, patch from Anton Kavalenka

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42582 4005530d-fff6-0310-9dd1-cebe43e6787f