specs: add cache_dir for the beaglebone armhf target
{build,initramfs}.include: do not export TMPDIR, causes problems to gcc-stage2
scripts: trivial comment removal
scripts: cross_glibc.sh: call build_src_prepare at the beginning
initramfs.include: use `find` to determine the kernel modules dir name
toolchain.include: cross_setup_environment: prepend our LD_LIBRARY_PATH
specs: build busybox dynamically, add libc to initramfs