CMake: Make it possible to use qt-cmake with --build and --installHEADdev

It wasn't possible to use the qt-cmake script with, e.g. the --build or
--install argument, because we called cmake with
-DCMAKE_TOOLCHAIN_FILE=..., and such arguments must be passed as the
first argument.

Since CMake 3.21 it's possible to pass the toolchain file via an
environment variable. This patch changes qt-cmake and qt-cmake.bat
accordingly.

This is safe, because we require CMake 3.22 for building Qt since Qt
6.9.

Pick-to: 6.10
Fixes: QTBUG-140785
Change-Id: I4b4bc729e80a0ab9fbe275cf2d3900111be3c1a3
Reviewed-by: Alexey Edelev <[email protected]>

0 files changed, 0 insertions, 0 deletions