Fix one of https://github.com/microsoft/vcpkg/issues/32398 issue.
```
CMake Error at mariadb_config/CMakeLists.txt:51 (GET_LIB_NAME):
GET_LIB_NAME Function invoked with incorrect arguments for function named:
GET_LIB_NAME
```
Fixed the issue that the search for iconv in Linux did not obtain the
value of the macro variable Iconv_LIBRARIES, causing the function input
parameter check to fail.
- [X] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [ ] ~~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.
Usage test pass with following triplets:
```
x64-linux
```
