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

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