Draft: meson: get Qt defines/linker flags matching to plugins we use

static plugins are not supported by the meson Qt module.

This works more or less like the code in configure.ac except we can parse the generate file directly in meson. meson doesn't seem to have regex for parsing strings so we use hardcoded string lengths.

The qmake-qt file needs to be generated in the source tree so we can use fs.read(). The cleanup is not handled as meson doesn't have a builtin way to create folders and remove files/folders. We could do the folder creation and cleanup in Python.

This leaves this files in the source folder:

• .qmake.stash
• qmake-qt
• qt6_plugin_import.cpp
• qt6_qml_plugin_import.cpp

Co-authored-by: Fatih Uzunoglu fuzun54@outlook.com

Draft on top of !6473 (merged) so the Windows Qt module fully builds after this MR.