This is a known issue with the compiler that shipped with NetBSD 2.0.
Can you try the following patch to the Makefile?

--- Makefile    30 Mar 2005 11:57:57 -0000      1.21
+++ Makefile    2 Apr 2005 11:55:38 -0000
@@ -23,9 +23,9 @@

 # Workaround for pkg/29825 -- older compilers apparently
 # have problems building this package.
-.if (${MACHINE_PLATFORM:MNetBSD-2.0*-*} != "")
+#.if (${MACHINE_PLATFORM:MNetBSD-2.0*-*} != "")
 BUILDLINK_TRANSFORM+=  rename:-O2:-O1
-.endif
+#.endif

 CONFIGURE_ARGS+=       --enable-nls
 CONFIGURE_ARGS+=       --enable-xinerama