omxil-core: update libomxil_base.pc

the internal header file is included without prefix of "omx/"
so the include path of CFlags should have postfix of "/omx"

issue isn't exposed before, maybe the reason is:
other component uses both omx core and util, while util's pc file has the postfix of "/omx"

gst-omx expose the issue when it uses omx core only
khronos header: sync/rebase header files to 1.1.2 revision

add OMX VERSION macro in OMX_Types.h (gst-omx check the version number)
add ext headers: OMX_CoreExt.h, OMX_ImageExt.h, OMX_ComponentExt.h
    (we haven't used them yet)
componentbase: update spec reversion

gst-omx requires khronos header file reversion 1.1.2
componentbase: do not use native buffer by default

gst-omx do not know the details of VideoRenderBuffer