The Qt Resource Compiler (rcc) has a command-line option
`--format-version` which has the default value 2.
The only difference from `--format-version 1` is adding a last modified
timestamp to the output file. That, in turn, forces us to use
`QT_RCC_SOURCE_DATE_OVERRIDE=1` to get deterministic builds.
This change makes rcc output always deterministic by using
`--format-version 1` option that makes usage of the
`QT_RCC_SOURCE_DATE_OVERRIDE` needless. Also it improves interaction
with ccache.
Co-authored-by: fanquake <fanquake@gmail.com>
This is a backport of core#21654
Depends on D13870