Revert "product/core: Install busybox, lrzsz, ffmpeg, x264"

This reverts commit 4e667d6eb79e93f89580fab7badddb7d92b5d111.
Revert "build: Build fs_get_stats even for TINY_ANDROID"

This reverts commit fd41a27425ff04f5673de77339b2adc8eb624b86.
Revert "build: Make sure boot.img depends on the kernel having been built"

This reverts commit 017a85be346a2ec19e059b33911313c4a837771a.