core/pkg-generic: sanitise FOO_OVERRIDE_SRCDIR

In case FOO_OVERRIDE_SRCDIR has trailing spaces, like so:
    FOO_OVERRIDE_SRCDIR = /path/to/sources\x20

we would end up with a rsync command like so:
    rsync -au /path/to/sources / /path/to/build/foo

which would effectively rsync the whole vfs, eventually filling the
whole disk... :-(

So, just qstrip the variable before use.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/pkg-generic.mk

@@ -102,7 +102,7 @@ $(BUILD_DIR)/%/.stamp_rsynced:
 	@$(call MESSAGE,"Syncing from source dir $(SRCDIR)")
 	@test -d $(SRCDIR) || (echo "ERROR: $(SRCDIR) does not exist" ; exit 1)
 	$(foreach hook,$($(PKG)_PRE_RSYNC_HOOKS),$(call $(hook))$(sep))
-	rsync -au $(RSYNC_VCS_EXCLUSIONS) $(SRCDIR)/ $(@D)
+	rsync -au $(RSYNC_VCS_EXCLUSIONS) $(call qstrip,$(SRCDIR))/ $(@D)
 	$(foreach hook,$($(PKG)_POST_RSYNC_HOOKS),$(call $(hook))$(sep))
 	$(Q)touch $@