Infer dependencies from download strategies and URLs

Closes #20849.
Closes #22871.
vim: hg dep is inferred
MercurialDownloadStrategy: handle corrupt checkouts
MercurialDownloadStrategy: pull quietly in non-verbose mode
SubversionDownloadStrategy: handle corrupt checkouts
Remove commented out code, this is in git after all
BazaarDownloadStrategy: handle corrupt checkouts
Move ld64 into SharedEnvExtension

Superenv is being tested on Xcode 3.1.4, so this needs to be supported
in both ENVs, not just stdenv.
Upgrading lzlib To Version 1.5

lzlib version 1.4 is no longer on this site and is 404'ing. Version 1.5 appears to be the latest release.

http://download.savannah.gnu.org/releases/lzip/

Closes #22916.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
plzip 1.1