libpq: Avoid broken symlinks in include/catalog

[scandyna]

Summary

Changes to recipe: libpq/[*]

Motivation

See #24895

Details

To avoid broken symlinks, do out of source build.
Change build() and package() method to do out of source build.
Copy the backend catalog from the source tree.
Note: the MSVC part is ignored in this PR.

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan

I ran the tests for some configurations:
https://gitlab.com/scandyna/conan-center-index-partialbasicci-sandbox/-/pipelines/1463949508

Notes about the Windows builds:

• For MSVC, the test_v1_package fails. Probably something missing in my environment (I don't use the cmake generator anymore)
• For MinGW, the test_package fails due to undefined references. This is also the case without the changes in this PR (I opened another issue for this case, 25282)

[CLAassistant]

All committers have signed the CLA.

[conan-center-bot]

Conan v1 pipeline ✔️

Warning

Conan Center will stop receiving updates for Conan 1.x packages soon - please see announcement.

All green in build 2 (3b5043ff57529db3a493724dae1d79f2801cf809):

• libpq/13.12:
  Built 20 packages out of 22 (All logs)

• libpq/10.23:
  Built 20 packages out of 22 (All logs)

• libpq/15.4:
  Built 20 packages out of 22 (All logs)

• libpq/15.5:
  Built 20 packages out of 22 (All logs)

• libpq/14.9:
  Built 20 packages out of 22 (All logs)

• libpq/12.16:
  Built 20 packages out of 22 (All logs)

• libpq/11.21:
  Built 20 packages out of 22 (All logs)

• libpq/15.3:
  Built 20 packages out of 22 (All logs)

• libpq/9.6.24:
  Built 20 packages out of 22 (All logs)

---

Conan v2 pipeline ✔️

Note: Conan v2 builds are now mandatory. Please read our discussion about it.

All green in build 2 (3b5043ff57529db3a493724dae1d79f2801cf809):

• libpq/15.4:
  All packages built successfully! (All logs)

• libpq/15.3:
  All packages built successfully! (All logs)

• libpq/14.9:
  All packages built successfully! (All logs)

• libpq/15.5:
  All packages built successfully! (All logs)

• libpq/13.12:
  All packages built successfully! (All logs)

• libpq/12.16:
  All packages built successfully! (All logs)

• libpq/11.21:
  All packages built successfully! (All logs)

• libpq/10.23:
  All packages built successfully! (All logs)

• libpq/9.6.24:
  All packages built successfully! (All logs)

[ErniGH]

LGTM