other (related) changes:
- kernel headers are now installed using "make headers_install" on 2.6
- target names now contain an openwrt "vendor" tag (e.g. mips-openwrt-linux-gnu)
- build directory names now contain gcc/libc name/version
- default cpu for x86 is now i486 (required to build glibc/eglibc)
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@13931 3c298f89-4303-0410-b956-a3cf2f4a3e73
