X11 build fixups

- fixed -Werror=misleading-indentation warning
- fixed -Werror=nonnull-compare warning on xll and QT builds
- PNG_LIBPNG_VER backward compatibily changes
- giflib backward compatibily changes
- resolved some undefs for X11 build
- silenced some small compile warnings in JGE Makefile
- added -DTIXML_USE_STL to remaining build types (PSP had it added)
- fixed x11 Boost incompatibility issue part of #548
- reworked PrecompiledHeader.h platforms used

JGE/src/JGE.cpp

@@ -249,6 +249,7 @@ u32 JGE::BindKey(LocalKeySym sym, JButton button)
 u32 JGE::UnbindKey(LocalKeySym sym, JButton button)
 {
     for (keycodes_it it = keyBinds.begin(); it != keyBinds.end(); )
+    {
         if (sym == it->first && button == it->second)
         {
             keycodes_it er = it;
@@ -256,7 +257,8 @@ u32 JGE::UnbindKey(LocalKeySym sym, JButton button)
             keyBinds.erase(er);
         }
         else ++it;
-        return keyBinds.size();
+    }
+    return keyBinds.size();
 }
 
 u32 JGE::UnbindKey(LocalKeySym sym)