core/download: do not hard-code the path to the package hash file

Now that packges may have hashes for their downloaded files in a
versioned subdir or in the unversioned hash file, we can no longer
hard-code the path to the package hash file anymore.

Instead, we now make use of the per-package variable, that points to the
package hash file.

Note: of the packages for which we offer a version choice, almost none,
but some of the qt5 ones, have a per-version hash file, so we still use
the unversioned hash file for them. As for the few qt5 packages that do
have a per-version hash file for their licensing terms, they've already
been updated to duplicate their download hashes in both the unversioned
and per-version hash files. So, one way or the other, no hash check
would go missing with this change.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

NOTE (eocanha):
This patch caused conflicts that I had to resolve. I just added the new way
usage of the new HASH_FILE variable to all the "-H" parameters used in the
file.

In the future, when we upgrade to a more recent buildroot (~Oct 2018)
supporting versioned hashes and conflicts appear, we should just revert
this patch and the previous one and use the code upstream.

Author: yann-morin-1998

package/pkg-download.mk

@@ -144,7 +144,7 @@ endef
 define DOWNLOAD_SCP
 	$(EXTRA_ENV) $(DL_WRAPPER) -b scp \
 		-o $(DL_DIR)/$(2) \
-		-H $(PKGDIR)/$($(PKG)_RAWNAME).hash \
+		-H '$($(PKG)_HASH_FILE)' \
 		$(QUIET) \
 		-- \
 		'$(call stripurischeme,$(call qstrip,$(1)))' \
@@ -175,7 +175,7 @@ endef
 define DOWNLOAD_WGET
 	$(EXTRA_ENV) $(DL_WRAPPER) -b wget \
 		-o $(DL_DIR)/$(2) \
-		-H $(PKGDIR)/$($(PKG)_RAWNAME).hash \
+		-H '$($(PKG)_HASH_FILE)' \
 		$(QUIET) \
 		-- \
 		'$(call qstrip,$(1))' \
@@ -189,7 +189,7 @@ endef
 define DOWNLOAD_LOCALFILES
 	$(EXTRA_ENV) $(DL_WRAPPER) -b cp \
 		-o $(DL_DIR)/$(2) \
-		-H $(PKGDIR)/$($(PKG)_RAWNAME).hash \
+		-H '$($(PKG)_HASH_FILE)' \
 		$(QUIET) \
 		-- \
 		$(call stripurischeme,$(call qstrip,$(1))) \