Add option to compile without btClock and without profiling: comment out USE_BT_CLOCK, and #define BT_NO_PROFILE
Fixed typo/case in #include "LinearMath/btQuickProf.h", in SpuParallelSolver.cpp
Removed unnecessary files from libxml CMakeLists.txt
* Unused variables.
* Missing newlines at ends of #included files.
* signed int loop variables where the termination condition is an unsigned 'get number of' function.
* 'NULL' used inappropriately for an integer or character constant (NULL is a pointer)
* abstract base classes with no virtual destructor.
* Floating point constants used to initialise integer variables.
