Layout code generates a lot of code and it may be beneficial not to
generate constraints if there is no constraints in that direction
Before the change:
cargo run -p slint-compiler -- examples/printerdemo_mcu/ui/printerdemo.slint -f rust | rustfmt | wc
40014 86643 2010535
cargo run -p slint-compiler -- examples/gallery/gallery.slint -f rust | rustfmt | wc
105715 229009 5434115
After this change:
cargo run -p slint-compiler -- examples/printerdemo_mcu/ui/printerdemo.slint -f rust | rustfmt | wc
38873 83654 1925830
cargo run -p slint-compiler -- examples/gallery/gallery.slint -f rust | rustfmt | wc
103817 224874 5316553
No measurable changes in compilation time.