If a call to `vcpkg_replace_string` makes no changes i.e doesn't
effectively replace a string, A warning is logged.
This should also help identify ports that no longer need these calls to
fix things in `.pc` files etc.
Fix#37096.
### Checklist
- [x] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [x] SHA512s are updated for each updated download.
- [ ] ~The "supports" clause reflects platforms that may be fixed by
this new version.~
- [ ] ~Any fixed [CI
baseline](https://github.com/microsoft/vcpkg/blob/master/scripts/ci.baseline.txt)
entries are removed from that file.~
- [ ] ~Any patches that are no longer applied are deleted from the
port's directory.~
- [x] The version database is fixed by rerunning `./vcpkg x-add-version
--all` and committing the result.
- [x] Only one version is added to each modified port's versions file.
### Test
Port usage tests pass with following triplets:
* x64-linux
