If you update the kernel headers tarball and run make against an already built

buildroot, the header files will be re-extracted, but they will not be put in
exactly the right place if the name of the extracted directory includes the
kernel version numbers.

For example, linux-libc-headers-2.4.25.tar.bz2 will be extracted to
$(TOOLCHAIN_BUILD_DIR)/linux-libc-headers-2.4.25, and then the mv command will
move the newly extracted headers into the already existing
$(TOOLCHAIN_BUILD_DIR)/linux directory, instead of replacing that directory as
desired.

The fix is to first remove the $(TOOLCHAIN_BUILD_DIR)/linux directory and then
do the mv command.

http://bugs.busybox.net/view.php?id=296

toolchain/kernel-headers/kernel-headers.mk

@@ -78,6 +78,7 @@ $(DL_DIR)/$(LINUX_HEADERS_SOURCE):
 	$(WGET) -P $(DL_DIR) $(LINUX_HEADERS_SITE)/$(LINUX_HEADERS_SOURCE)
 
 $(LINUX_HEADERS_DIR)/.unpacked: $(DL_DIR)/$(LINUX_HEADERS_SOURCE)
+	rm -rf $(LINUX_HEADERS_DIR)
 	mkdir -p $(TOOL_BUILD_DIR)
 	bzcat $(DL_DIR)/$(LINUX_HEADERS_SOURCE) | tar -C $(TOOL_BUILD_DIR) $(TAR_OPTIONS) -
 ifneq ($(LINUX_HEADERS_UNPACK_DIR),$(LINUX_HEADERS_DIR))