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 _LMUSEFLG_H
#define _LMUSEFLG_H
#if __GNUC__ >=3
#pragma GCC system_header
#endif

#define USE_NOFORCE 0
#define USE_FORCE 1
#define USE_LOTS_OF_FORCE 2
#endif