Fix some issues reported by lintian

Fix some issues reported by lintian

• Update lintian override info format in d/source/lintian-overrides on line 2-7. (mismatched-override)
• Add missing build dependency on asterisk-dev for command dh_asterisk. (missing-build-dependency-for-dh_-command)
• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/asterisk-flite/d8f21194-9e7c-4c2a-9ce5-8f141cc9ad5c.

Debdiff

These changes affect the binary packages:

[The following lists of changes regard files as different if they have different names, permissions or owners.]

Files in second set of .debs but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/74/387355fe5b3a166b0b4b39f987e24a3925c7a5.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/2e/3865b832438fd28a919d002c4cfe6c5348b7f9.debug

No differences were encountered between the control files of package **asterisk-flite**

Control files of package asterisk-flite-dbgsym: lines which differ (wdiff format)

• Build-Ids: 2e3865b832438fd28a919d002c4cfe6c5348b7f9 74387355fe5b3a166b0b4b39f987e24a3925c7a5

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