Do not #define pi on marble sources, use M_PI instead.
Review Request #114529 - Created Dec. 18, 2013 and submitted
This patch changes #define pi to M_PI - even knowing that it's not the standard, it's what most people should look like when looking for 'pi', and that define actually broke Marble's compilation on Qt5 because a QVariant used a variable named 'pi' internally that didn't had a thing to do with the math constant... ;p
None - there are other errors that I need to fix for Qt5 before I actually test it. but since it was just a definition change, I doub't it created any regressions.