ext-toolchain: fix ct-ng as external rsync issues

When using a CT-NG toolchain as external toolchain (not with the
integration) and said toolchain has u-w directories rsync fails.
So instruct rsync to chmod u+w directories in the target copy to avoid
the issue.

[Peter: notice that this is a workaround for a rsync 3.0.8 bug]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/helpers.mk

@@ -91,7 +91,7 @@ copy_toolchain_sysroot = \
 	ARCH_SUBDIR="$(strip $3)"; \
 	for i in etc lib sbin usr ; do \
 		if [ -d $${ARCH_SYSROOT_DIR}/$$i ] ; then \
-			rsync -au --exclude 'usr/lib/locale' $${ARCH_SYSROOT_DIR}/$$i $(STAGING_DIR)/ ; \
+			rsync -au --chmod=Du+w --exclude 'usr/lib/locale' $${ARCH_SYSROOT_DIR}/$$i $(STAGING_DIR)/ ; \
 		fi ; \
 	done ; \
 	if [ `readlink -f $${SYSROOT_DIR}` != `readlink -f $${ARCH_SYSROOT_DIR}` ] ; then \