Make clean work when a recipe has no recipe.sh.

See merge request redox-os/cookbook!243

Previously, one had to have a recipe.sh in all recipe directories in
order to run `make clean` successfully. This fixes that.

Signed-off-by: Wren Turkal <wt@penguintechs.org>

Specify --locked to ensure reproducibility

See merge request !241

Needed to stop mass-errors for us mortals without the latest rust
version, ever since redox_syscall 0.1.57 was merged.

Add libexpat to GDB

See merge request !240

Update gnu-binutils to compile GDB as well

See merge request !239

Add gdbserver recipe

See merge request !238