Hi, sometimes is desirable to know all builtins that are being 
used on pkgsrc (at least I wanted to know an easy way to
detect this), the following patch show all used builtins in
packages, e.g:

[/usr/pkgsrc/graphics/gimp]> make show-var VARNAME=SHOW_BUILTIN
 bzip2heimdal openssl db1 gettext iconv zlib pthread 
[usr/ pkgsrc/graphics/gimp]>


Index: buildlink3/bsd.builtin.mk
===================================================================
RCS file: /cvsroot/pkgsrc/mk/buildlink3/bsd.builtin.mk,v
retrieving revision 1.3
diff -u -r1.3 bsd.builtin.mk
--- buildlink3/bsd.builtin.mk   10 Nov 2004 17:39:03 -0000      1.3
+++ buildlink3/bsd.builtin.mk   24 May 2005 15:18:46 -0000
@@ -146,4 +146,9 @@
 #
 .for _pkg_ in ${BUILDLINK_PACKAGES}
 USE_BUILTIN.${_pkg_}?= no
+SHOW_BUILTIN?=         # empty
+.  if !empty(USE_BUILTIN.${_pkg_}:M[Yy][Ee][Ss])
+SHOW_BUILTIN+=         ${_pkg_}
+.  endif
 .endfor
+

Is ok to commit?