[source] ar71xx: fix kernel relocate stub parallel build issue

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/462a7c0e96d70ba82dfb5ddd41c82b66c3261ca2

commit 462a7c0e96d70ba82dfb5ddd41c82b66c3261ca2
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Tue Nov 8 11:50:50 2016 +0100

    ar71xx: fix kernel relocate stub parallel build issue
    
    Use per-kernel directory
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 target/linux/ar71xx/image/Makefile | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/target/linux/ar71xx/image/Makefile b/target/linux/ar71xx/image/Makefile
index 26e9558..64221a3 100644
--- a/target/linux/ar71xx/image/Makefile
+++ b/target/linux/ar71xx/image/Makefile
@@ -79,15 +79,16 @@ define Build/loader-okli
 endef
 
 define Build/relocate-kernel
-	rm -rf $(KDIR)/relocate
-	$(CP) ../../generic/image/relocate $(KDIR)
-	$(MAKE) -C $(KDIR)/relocate KERNEL_ADDR=$(KERNEL_LOADADDR) CROSS_COMPILE=$(TARGET_CROSS)
+	rm -rf $@.relocate
+	$(CP) ../../generic/image/relocate $@.relocate
+	$(MAKE) -j1 -C $@.relocate KERNEL_ADDR=$(KERNEL_LOADADDR) CROSS_COMPILE=$(TARGET_CROSS)
 	( \
-		dd if=$(KDIR)/relocate/loader.bin bs=32 conv=sync && \
+		dd if=$@.relocate/loader.bin bs=32 conv=sync && \
 		perl -e '@s = stat("$@"); print pack("N", @s[7])' && \
 		cat "$@" \
 	) > "$@.new"
 	mv "$@.new" "$@"
+	rm -rf $@.relocate
 endef
 
 define Build/copy-file