pkg-infra: also set PKGDIR for the download step

This will be needed to get the hash file, to check the
downloaded files.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pkg-generic.mk

@@ -602,6 +602,7 @@ $$($(2)_TARGET_PATCH):			RAWNAME=$$(patsubst host-%,%,$(1))
 $$($(2)_TARGET_PATCH):			PKGDIR=$(pkgdir)
 $$($(2)_TARGET_EXTRACT):		PKG=$(2)
 $$($(2)_TARGET_SOURCE):			PKG=$(2)
+$$($(2)_TARGET_SOURCE):			PKGDIR=$(pkgdir)
 $$($(2)_TARGET_DIRCLEAN):		PKG=$(2)
 
 # Compute the name of the Kconfig option that correspond to the