lpmake: Add a flag to force building a complete, empty super.img.

Normally lpmake without images is used to generate super_empty.img, but
it is useful to also generate a fully sparse super_empty for flashing in
the bootloader. This patch adds a --force-full-image flag to provide this.

Bug: N/A
Test: lpmake --force-full-image
Change-Id: Ica55a7b35f6e1a0282e5a9305f1a3e4b5028755b
1 file changed