(found while searching for the build error on armhf/armel on Debian
buildds, once resolved will make an additional PR for that.)
$grep -r GL_MULTISAMPLE src/
yields:
src/Mod/Sandbox/Gui/Overlay.cpp: #ifndef GL_MULTISAMPLE
src/Mod/Sandbox/Gui/Overlay.cpp: #define GL_MULTISAMPLE 0x809D
src/Mod/Sandbox/Gui/GLGraphicsView.cpp:#ifndef GL_MULTISAMPLE
src/Mod/Sandbox/Gui/GLGraphicsView.cpp:#define GL_MULTISAMPLE 0x809D
-> The defines are defined, but never used in the compilation unit
debca05df4