Remove the -Csoft-float argument when building the kernel

See merge request !392

The targets specify the soft-float ABI already and -Csoft-float should likely
have never existed in the first place. It is unsound to mix crates compiled
with different float ABI's and the only stable way to get all crates to agree
on the soft float ABI is by specifying a target which uses the soft float ABI
anyway even without explicit -Csoft-float.

See also https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/.60-Csoft-float.60.20considered.20harmful

Update GNU make to v4.4 and create new recipe and new patch.

See merge request !390

Make perl5 recipe to build perl 5.40.

See merge request !389

Migrate the book recipe to /usr

See merge request !385

Add the website recipe

See merge request !386

Fix fetch.sh for subdirs

See merge request !387

Document the TODO for working recipes

See merge request !388

Launch ffplay on video and audio MIME types in Orbital programs

See merge request !384

Move ps2d invocation after the logging ramfs is created

See merge request !383

Fix the xz recipe

See merge request !382

This is necessary for ps2d to use redox-log.

Remove the TMPDIR env var

See merge request !381