Remove -lpthread and -ldl from the configure checking for Boehm GC.

This is for PR #29012 from Douglas Brebner.

I reported this to the inkscape developers and this is being fixed.

graphics/inkscape/distinfo

@@ -1,4 +1,5 @@
-$NetBSD: distinfo,v 1.2 2005/01/12 20:54:52 reed Exp $
+$NetBSD: distinfo,v 1.3 2005/01/19 21:54:26 reed Exp $
 
 SHA1 (inkscape-0.40.tar.bz2) = 1dc713442abc887343c9dd966a7ea7470023036b
 Size (inkscape-0.40.tar.bz2) = 3822704 bytes
+SHA1 (patch-aa) = 3042766f99f4bd643c14e73a4774cf870891550a

graphics/inkscape/patches/patch-aa

@@ -0,0 +1,13 @@
+$NetBSD: patch-aa,v 1.3 2005/01/19 21:54:26 reed Exp $
+
+--- configure.orig	2004-11-28 23:21:53.000000000 -0800
++++ configure
+@@ -21463,7 +21463,7 @@ if test "${ac_cv_lib_gc_GC_malloc+set}" 
+   echo $ECHO_N "(cached) $ECHO_C" >&6
+ else
+   ac_check_lib_save_LIBS=$LIBS
+-LIBS="-lgc -lpthread -ldl $LIBS"
++LIBS="-lgc $LIBS"
+ cat >conftest.$ac_ext <<_ACEOF
+ /* confdefs.h.  */
+ _ACEOF