Win32 optimized build : xp_core.h

Following the instruction given in Win32 build page, I reset MOZ_DEBUG
and set MOZ_PROFILE to 1.  The build stopped complaining that xp_core.h
couldn't be found. It's indeed absent in my local tree. Then, I turned
to lxr, but Lxr search for xp_core.h came up with nothing.  Then, I
searched for any article about it in this newsgroup and only thread I
found was over two years ago (in 1999). it seems like xp_core.h have
gone away since. Then, why do I get the error message as below? 

+++make: export in C:\works\moz\mozilla\xpfe\bootstrap
+++make: libs in C:\works\moz\mozilla\config
+++make: libs in C:\works\moz\mozilla\include
+++make: libs in C:\works\moz\mozilla\jpeg
NMAKE : fatla error U1073: don't know how to make `..\dist\include\xp_core.h`

  I've had no problem with making a debug build. I also tried
with MOZ_PROFILE unset, but that didn't make any difference. 

   Thank you in advance for helping me with this problem,

   Jungshik Shin