[yamls2obj][test] - Make the Archives/regular.yaml test stricter.

In rG6d656c9691d4 I had to relax the check from

`CONTENT: 21 3c 61 72 63 68 3e 0a 12{{$}}`

to

`CONTENT: 21 3c 61 72 63 68 3e 0a 12`

to fix the FreeBSD bot quickly: http://lab.llvm.org:8011/#/builders/28/builds/547

It turns out that "od" prints a trailing white space on FreeBSD, that is
why EOL mark ({{$}}) can't be used. But we still want to check the output size.

This patch adds a check of output size with "wc -c", similar to how it is done
below in the same test. This restores the original strictness.