Add Callbacks.h to list of files to be copied to a dist tarball.

git-svn-id: https://svn.r-project.org/R/trunk@89103 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: luke

src/include/Makefile.in

@@ -20,7 +20,7 @@ OBJ_HEADERS = Rconfig.h Rmath.h Rversion.h
 INT_HEADERS = Defn.h Errormsg.h Fileio.h Graphics.h GraphicsBase.h \
    IOStuff.h Internal.h Parse.h Print.h Rconnections.h \
    Rdynpriv.h Rgraphics.h Rinlinedfuns.h Startup.h rlocale.h \
-   PrtUtil.h
+   Callbacks.h PrtUtil.h
 
 DISTFILES = Makefile.in Makefile.win $(INT_HEADERS) $(SRC_HEADERS) \
   config.h.in stamp-h.in Rmath.h0.in