Override git sha1 implementation

Fix pastel recipe; add 'mkdir'

Add recipe for uutils findutils

Recipe for sed

Detecting find and stat from Homebrew/MacPorts on macOS

available this causes problems in macOS which has an
BSD userland. With these changes we will use the GNU
`find` and `stat` installed by the now modified boostrap
script on https://github.com/redox-os/redox/pull/995.

Details

- Using `find` from Homebrew/MacPorts `findutils` package on macOS.
- Using `stat` from Homebrew/MacPorts `coreutils` package on macOS.

Recipe for gawk

Remove some changes to python that are unneeded now

Add rustual-boy recipe

Fix repo.sh call for build depends

This reverts commit 1a67b4b2.

Recipe for nasm

git: use symlink instead of hard link

[WIP] Git recipe