xbps-src: remove proot chroot-style

proot is broken and result in random hard to debug issues,
this is the best way to not have new users use it.

README.md

@@ -51,7 +51,6 @@ multiple utilities to accomplish this task:
  - `ethereal` - only useful for one-shot containers, i.e docker (used with CI).
  - `xbps-uunshare(1)` - XBPS utility that uses `user_namespaces(7)` (part of xbps, default).
  - `xbps-uchroot(1)` - XBPS utility that uses `namespaces` and must be `setgid` (part of xbps).
- - `proot(1)` - utility that implements chroot/bind mounts in user space, see https://proot-me.github.io/.
 
 > NOTE: `xbps-src` does not allow building as root anymore. Use one of the chroot
 methods shown above.
@@ -136,17 +135,6 @@ If for some reason it's erroring out as `ERROR clone (Operation not permitted)`,
 your user is a member of the required `group` and that `xbps-uchroot(1)` utility has the
 proper permissions and owner/group as explained above.
 
-#### proot(1)
-
-The `proot(1)` utility implements chroot and bind mounts support completely in user space,
-and can be used if your Linux kernel does not have support for namespaces. See https://proot-me.github.io/.
-for more information.
-
-To enable it:
-
-    $ cd void-packages
-    $ echo XBPS_CHROOT_CMD=proot >> etc/conf
-
 <a name="install-bootstrap"></a>
 ### Install the bootstrap packages
 
@@ -404,7 +392,7 @@ checksum of the downloaded file matches the one specified in the template.
 Ultimately, if no mirror carries the distfile, or in case all downloads failed the
 checksum verification, the original download location is used.
 
-If you use `proot` or `uchroot` for your XBPS_CHROOT_CMD, you may also specify a local path
+If you use `uchroot` for your XBPS_CHROOT_CMD, you may also specify a local path
 using the `file://` prefix or simply an absolute path on your build host (e.g. /mnt/distfiles).
 Mirror locations specified this way are bind mounted inside the chroot environment
 under $XBPS_MASTERDIR and searched for distfiles just the same as remote locations.