Move GLES20 source into standard locations
Move Khronos headers into their respective components, to be exported by each.
Remove hostthreadadapter as nothing outside of the vghwapiwrapper, which now contains the code, needs it
#ifndef _INITGUID_H
#define _INITGUID_H
#if __GNUC__ >=3
#pragma GCC system_header
#endif
#ifndef DEFINE_GUID
#include <basetyps.h>
#endif
#undef DEFINE_GUID
#define DEFINE_GUID(n,l,w1,w2,b1,b2,b3,b4,b5,b6,b7,b8) GUID_EXT const GUID n GUID_SECT = {l,w1,w2,{b1,b2,b3,b4,b5,b6,b7,b8}}
#endif