Fix #29274: problem compiling cycles opencl kernel from directory with spaces.

Some drivers don't support passing include paths with spaces in them, nor does
the opencl spec specify anything about how to quote/escape such paths, so for
now we just resolved #includes ourselves. Alternative would have been to use c
preprocessor, but this also resolves all #ifdefs, which we do not want.

intern/cycles/kernel/kernel.cl

@@ -25,7 +25,6 @@
 
 #include "kernel_film.h"
 #include "kernel_path.h"
-//#include "kernel_displace.h"
 
 __kernel void kernel_ocl_path_trace(
 	__constant KernelData *data,