fix symlink install of busybox so that it happens even on parallel builds (#394)

Makefile

@@ -394,20 +394,6 @@ $(foreach m, $(modules-y), \
 	$(call map,initrd_lib_add,$(call libs,$m)) \
 )
 
-# hack to install busybox into the initrd if busybox is configured
-ifeq "$(CONFIG_BUSYBOX)" "y"
-initrd_bins += $(initrd_bin_dir)/busybox
-endif
-
-$(initrd_bin_dir)/busybox: $(build)/$(busybox_dir)/busybox
-	$(do,SYMLINK,$@,$(MAKE) \
-		-C $(build)/$(busybox_dir) \
-		CC="$(heads_cc)" \
-		CONFIG_PREFIX="$(pwd)/initrd" \
-		$(MAKE_JOBS) \
-		install \
-	)
-
 #
 # hack to build cbmem from coreboot
 # this must be built *AFTER* musl, but since coreboot depends on other things

modules/busybox

@@ -13,8 +13,24 @@ busybox_config := config/busybox.config
 busybox_output := busybox
 busybox_target := \
 	$(CROSS_TOOLS) \
-	CONFIG_PREFIX="$(initrd_tmp_dir)" \
 	$(MAKE_JOBS) \
-	install
+
+# Install symlinks when the busybox program is installed
+
+ifeq "$(CONFIG_BUSYBOX)" "y"
+initrd_bins += $(initrd_bin_dir)/busybox
+endif
+
+$(initrd_tmp_dir)/bin/busybox: $(build)/$(busybox_dir)/.build
+	$(call do,SYMLINK,bin/busybox,\
+		$(MAKE) \
+			-C $(build)/$(busybox_dir) \
+			CC="$(heads_cc)" \
+			CONFIG_PREFIX="$(initrd_bin_dir)/.." \
+			install \
+		| tee -a $(build)/log/busybox.log \
+		$(VERBOSE_REDIRECT) \
+	)
+
 
 busybox_depends := $(musl_dep)