Qt6Core fails to load libQt6Core.so.6 when running uic during compilation

I'm trying to compile Qt6 from source for Alpine Linux. Using the regular CMake build commands as listed below, it fails to load `libQt6Core.so.6` when running `uic`. However, `libQt6Core.so.6` has been built and is available in the right directories, so I'm unsure why it fails to load it.

```

cmake -B build \
-DCMAKE_BUILD_TYPE=None \
-DCMAKE_INSTALL_PREFIX=/usr \
-DINSTALL_BINDIR=lib/qt6/bin \
-DINSTALL_DOCDIR=share/doc/qt6 \
-DINSTALL_ARCHDATADIR=lib/qt6 \
-DINSTALL_DATADIR=share/qt6 \
-DINSTALL_INCLUDEDIR=include/qt6 \
-DINSTALL_MKSPECSDIR=lib/qt6/mkspecs \
-DINSTALL_EXAMPLESDIR=share/doc/qt6/examples \
-DQT_FEATURE_journald=OFF \
-DQT_FEATURE_openssl_linked=ON

cmake --build build

```

A full build log can be found at https://gitlab.alpinelinux.org/PureTryOut/aports/-/jobs/265912.

The error:

```
AutoUic subprocess error
------------------------
The uic process failed to compile
"SRC:/src/widgets/dialogs/qfiledialog.ui"
into
"SRC:/build/src/widgets/Widgets_autogen/include/ui_qfiledialog.h"
included by
"SRC:/src/widgets/dialogs/qfiledialog.cpp"
Command
-------
/builds/PureTryOut/aports/testing/qt6-qtbase/src/qtbase-everywhere-src-6.0.0/build/lib/qt6/bin/uic -o /builds/PureTryOut/aports/testing/qt6-qtbase/src/qtbase-everywhere-src-6.0.0/build/src/widgets/Widgets_autogen/include/ui_qfiledialog.h /builds/PureTryOut/aports/testing/qt6-qtbase/src/qtbase-everywhere-src-6.0.0/src/widgets/dialogs/qfiledialog.ui
Output
------
Error loading shared library libQt6Core.so.6: No such file or directory (needed by /builds/PureTryOut/aports/testing/qt6-qtbase/src/qtbase-everywhere-src-6.0.0/build/lib/qt6/bin/uic)
Error relocating /builds/PureTryOut/aports/testing/qt6-qtbase/src/qtbase-everywhere-src-6.0.0/build/lib/qt6/bin/uic: _ZN5QChar8categoryEDi: symbol not found

...

```