qt-build-utils writes the collected path verbatim as the qrc alias, and
read_dir joins with a backslash on Windows, so none of the 1469 aliases
resolved: 1106 icons, 9 fonts and 21 shaders would each fail with
"Cannot open". Normalise only when the build host is Windows, since a
backslash is a legal filename character on Unix.
Also probe qsb.exe and QT_ROOT_DIR/bin, because Path::is_file never
appends .exe, and fix the SpectrumBand hand-bake comment, whose command
lacked --hlsl 50 and the GLES variants that build.rs actually passes.
cc
vicrodh
6beb1e695e