Bug 1298855 - part 2 - remove prcpucfg.h #include from xpt_arena.h; r=erahm

Nothing else in this code requires prcpucfg.h at this point, and we
might as well remove nspr.h from xpt_xdr.cpp while we're at it.

xpcom/typelib/xpt/xpt_arena.h

@@ -10,7 +10,6 @@
 #ifndef __xpt_arena_h__
 #define __xpt_arena_h__
 
-#include "prcpucfg.h"
 #include <stdlib.h>
 #include "mozilla/Attributes.h"
 #include "mozilla/MemoryReporting.h"

xpcom/typelib/xpt/xpt_xdr.cpp

@@ -6,7 +6,6 @@
 /* Implementation of XDR primitives. */
 
 #include "xpt_xdr.h"
-#include "nspr.h"
 #include "nscore.h"
 #include <string.h>             /* strchr */
 #include "mozilla/EndianUtils.h"