In most cases instead pass `for_machine`, the name of the relevant
machines (what compilers target, what targets run on, etc). This allows
us to use the cross code path in the native case, deduplicating the
code.
As one can see, environment got bigger as more information is kept
structured there, while ninjabackend got a smaller. Overall a few amount
of lines were added, but the hope is what's added is a lot simpler than
what's removed.
It doesn't make much sense to have this and not also have
cross-compilers (so any use of this is already pretty suspect as
probably wrong when cross-compiling).
This information is accessible anyhow via environment.coredata.
This new cmake module allows to generate cmake package files. This may ease the
porting for cmake projects that are exporting cmake package informations for other
depending projects. The module uses as much as possible the templates provided by
the cmake installation (and so cmake needs to be installed).