Revert "[cmx] reduce validate_cmx deps to just cmx"

This reverts commit 6db6974b3cdad37d1b74dff52fe62a1d2dbc69a5.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [cmx] reduce validate_cmx deps to just cmx
> 
> This gets rid of the issue where a target A that has cmx files might
> depend on target B, where target B has a restricted visibility list only
> to A. Thus A isn't visible to validate_cmx.
> 
> Follow up to https://fuchsia-review.git.corp.google.com/c/build/+/196740
> 
> TESTED=built all layers
> 
> CF-129 #comment
> 
> Change-Id: Ic0263ce4e893d8e88d2f0573af2f31d93df545fd

TBR=shayba@google.com,leolung@google.com,dgonyeo@google.com

Change-Id: I115ba073482005f1d5fcc84ca4774e70948418e8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
1 file changed