f0cebbdb2a1a3c2f0facd88963484ad6fd5851db qt: enable -ltcg for windows HOST (fanquake)
Pull request description:
Patch around multiple definition issues in Qt, and enable `-ltcg` when using `LTO=1`.
Split from #25391.
ACKs for top commit:
hebasto:
ACK f0cebbdb2a1a3c2f0facd88963484ad6fd5851db
Tree-SHA512: 2d6e34779f360bf6dfea4f70fc9004a16e95da79716fcb3046afbf2b01317b7e16965cb51b967b7b5fb64549306c5f48cf59082884289c52016bc1e86949e062
