Fix using dependencies from Ports in FreeBSD that are not searched with pkg-config

[native-api]

Make sure you have checked all steps below.

Prerequisite

• Please consider implementing the feature as a hook script or plugin as a first step.
  • pyenv has some powerful support for plugins and hook scripts. Please refer to Authoring plugins for details and try to implement it as a plugin if possible.
• Please consider contributing the patch upstream to rbenv, since we have borrowed most of the code from that project.
  • We occasionally import the changes from rbenv. In general, you can expect changes made in rbenv will be imported to pyenv too, eventually.
  • Generally speaking, we prefer not to make changes in the core in order to keep compatibility with rbenv.
• My PR addresses the following pyenv issue (if any)
  • Closes Readline issues on new install of FreeBSD 13.1 #2585

Description

• Here are some details about my PR

Reworked #2586 . It turns out, only some deps are searched by CPython's Configure with pkg-config. At least Readline and Sqlite3 aren't (this is fixed for readline in 3.12.0a1 and for sqlite3 in 3.11.0a3).

Tests

• My PR adds the following unit tests (if any)

• Tests for added logic