taint_analysist isn't a messaget [blocks: #3800]

[tautschnig]

Pass a message handler to the methods that use it. Also make use of
conditional_output to avoid generating a debug string (instead of just not
printing it).

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 79ccaa3).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/99552621

[kroening]

Argument lists are getting long -- simply make that log a member?

[tautschnig]

Argument lists are getting long -- simply make that log a member?

Done!

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 17d7dbb).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/100292616

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 38f23b0).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/102433787

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: f8b49a0).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/103463260