Add explicit -lfoo for libraries that are required because of NEEDED

entries in other libraries.
This avoids a bug in 'ld' which causes it to look in the directory
specified by the RPATH entry (in the library with the NEEDED entry)
without adding the directory supplied by --sysroot.
When the RPATH entry in blindly folloed the link is done w.r.t the
systems own libfoo.so which may be missing some symbols.
(Or might have a wrong sized data area that would need copying
into the programs (or other libraries) data space.)
ld also seems to add a NEEDED entry for these libraries directly
into the program binary - this doesn't seem right to me.
Fixes my build where the installed libX11.so is dated from 2009.
CVS :----------------------------------------------------------------------

external/mit/xorg/bin/xdm/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.6 2009/12/18 17:28:47 christos Exp $
+#	$NetBSD: Makefile,v 1.7 2011/05/23 17:44:41 dsl Exp $
 
 .include <bsd.own.mk>
 
@@ -27,7 +27,7 @@ CPPFLAGS.resource.c=	\
 	-DDEF_GREETER_LIB=\"${XDMGREETERLIB}\"
 
 LDADD+=		-lXau -lXdmcp -lXft -lXinerama -lXpm
-LDADD+=		-lXmu -lXt -lSM -lICE -lXext -lX11
+LDADD+=		-lXmu -lXt -lSM -lICE -lXext -lXrender -lX11
 LDADD+=		-lcrypt -lfreetype
 DPADD+=		${LIBXAU} ${LIBXDMCP} ${LIBXFT} ${LIBXINERAMA} ${LIBXPM}
 DPADD+=		${LIBXMU} ${LIBXT} ${LIBSM} ${LIBICE} ${LIBXEXT} ${LIBX11}

external/mit/xorg/bin/xinput/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.4 2010/05/22 02:40:55 mrg Exp $
+#	$NetBSD: Makefile,v 1.5 2011/05/23 17:44:41 dsl Exp $
 
 .include <bsd.own.mk>
 
@@ -8,7 +8,7 @@ SRCS=	buttonmap.c feedback.c list.c property.c setint.c setmode.c \
 
 CPPFLAGS+=	-DVERSION='"1.4.0"'
 
-LDADD+=	-lXi -lm
+LDADD+=	-lXi -lX11 -lm
 DPADD+=	${LIBXI} ${LIBM}
 .PATH:	${X11SRCDIR.${PROG}}/src
 .PATH:	${X11SRCDIR.${PROG}}/man