Dep/G3D: Fix a typo in Vector3int32 += operator

dep/g3dlite/Readme.txt

@@ -8,3 +8,4 @@ G3D-v8.0_hotfix4.diff - 2012-11-09 - fix compilation on OSX
 G3D-v8.0_hotfix5.diff - 2013-02-27 - fix compilation in cygwin environments
 G3D-v8.0_hotfix6.diff - 2013-03-08 - fix compilation in mingw
 G3D-v8.0_hotfix7.diff - 2013-08-31 - fix typo in Matrix4 == operator
+G3D-v8.0_hotfix8.diff - 2013-09-01 - fix typo in Vector3int32 += operator

dep/g3dlite/include/G3D/Vector3int32.h

@@ -74,7 +74,7 @@ public:
     inline Vector3int32& operator+=(const Vector3int32& other) {
         x += other.x;
         y += other.y;
-        z += other.y;
+        z += other.z;
         return *this;
     }