[source] build: cleanup tmp/ dir of target rootfs

[LEDE Commits]

yousong pushed a commit to source.git, branch master:
https://git.lede-project.org/dac629f71093715ea002c7949a9888188e58984e

commit dac629f71093715ea002c7949a9888188e58984e
Author: Yousong Zhou <yszhou4tech at gmail.com>
AuthorDate: Sun Mar 5 16:17:17 2017 +0800

    build: cleanup tmp/ dir of target rootfs
    
    Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
---
 include/rootfs.mk | 1 +
 package/Makefile  | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/rootfs.mk b/include/rootfs.mk
index c014b1d..74785cb 100644
--- a/include/rootfs.mk
+++ b/include/rootfs.mk
@@ -80,6 +80,7 @@ define prepare_rootfs
 	@-find $(1) -name .svn  | $(XARGS) rm -rf
 	@-find $(1) -name .git  | $(XARGS) rm -rf
 	@-find $(1) -name '.#*' | $(XARGS) rm -f
+	rm -rf $(1)/tmp/*
 	rm -f $(1)/usr/lib/opkg/lists/*
 	rm -f $(1)/usr/lib/opkg/info/*.postinst*
 	rm -f $(1)/usr/lib/opkg/info/*.prerm*
diff --git a/package/Makefile b/package/Makefile
index ac8faec..4fdf415 100644
--- a/package/Makefile
+++ b/package/Makefile
@@ -63,7 +63,7 @@ endif
 $(curdir)/install: $(TMP_DIR)/.build $(curdir)/merge $(if $(CONFIG_TARGET_PER_DEVICE_ROOTFS),$(curdir)/merge-index)
 	- find $(STAGING_DIR_ROOT) -type d | $(XARGS) chmod 0755
 	rm -rf $(TARGET_DIR) $(TARGET_DIR_ORIG)
-	[ -d $(TARGET_DIR)/tmp ] || mkdir -p $(TARGET_DIR)/tmp
+	mkdir -p $(TARGET_DIR)/tmp
 	$(call opkg,$(TARGET_DIR)) install \
 		$(call opkg_package_files,$(shell cat $(PACKAGE_INSTALL_FILES) 2>/dev/null))
 	@for file in $(PACKAGE_INSTALL_FILES); do \