kernel: fix downloading rcX releases

They are no longer stored in the "testing" subdirectory and are not
available as .tar.xz archives. If -rc is detected download it from the
git.kernel.org and use .tar.gz.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

include/kernel-defaults.mk

@@ -21,16 +21,22 @@ export HOST_EXTRACFLAGS=-I$(STAGING_DIR_HOST)/include
 # defined in quilt.mk
 Kernel/Patch:=$(Kernel/Patch/Default)
 
+ifneq (,$(findstring .xz,$(LINUX_SOURCE)))
+  LINUX_CAT:=xzcat
+else
+  LINUX_CAT:=zcat
+endif
+
 ifeq ($(strip $(CONFIG_EXTERNAL_KERNEL_TREE)),"")
   ifeq ($(strip $(CONFIG_KERNEL_GIT_CLONE_URI)),"")
     define Kernel/Prepare/Default
-	xzcat $(DL_DIR)/$(LINUX_SOURCE) | $(TAR) -C $(KERNEL_BUILD_DIR) $(TAR_OPTIONS)
+	$(LINUX_CAT) $(DL_DIR)/$(LINUX_SOURCE) | $(TAR) -C $(KERNEL_BUILD_DIR) $(TAR_OPTIONS)
 	$(Kernel/Patch)
 	$(if $(QUILT),touch $(LINUX_DIR)/.quilt_used)
     endef
   else
     define Kernel/Prepare/Default
-	xzcat $(DL_DIR)/$(LINUX_SOURCE) | $(TAR) -C $(KERNEL_BUILD_DIR) $(TAR_OPTIONS)
+	$(LINUX_CAT) $(DL_DIR)/$(LINUX_SOURCE) | $(TAR) -C $(KERNEL_BUILD_DIR) $(TAR_OPTIONS)
     endef
   endif
 else

include/kernel.mk

@@ -59,8 +59,15 @@ else
 
   LINUX_KERNEL:=$(KERNEL_BUILD_DIR)/vmlinux
 
-  LINUX_SOURCE:=linux-$(LINUX_VERSION).tar.xz
+  ifneq (,$(findstring -rc,$(LINUX_VERSION)))
-  ifeq ($(call qstrip,$(CONFIG_EXTERNAL_KERNEL_TREE))$(call qstrip,$(CONFIG_KERNEL_GIT_CLONE_URI)),)
+      LINUX_SOURCE:=linux-$(LINUX_VERSION).tar.gz
+  else
+      LINUX_SOURCE:=linux-$(LINUX_VERSION).tar.xz
+  endif
+
+  ifneq (,$(findstring -rc,$(LINUX_VERSION)))
+      LINUX_SITE:=https://git.kernel.org/torvalds/t
+  else ifeq ($(call qstrip,$(CONFIG_EXTERNAL_KERNEL_TREE))$(call qstrip,$(CONFIG_KERNEL_GIT_CLONE_URI)),)
       LINUX_SITE:=@KERNEL/linux/kernel/v$(word 1,$(subst ., ,$(KERNEL_BASE))).x
   else
       LINUX_UNAME_VERSION:=$(strip $(shell cat $(LINUX_DIR)/include/config/kernel.release 2>/dev/null))