This replaces all of the Apache blurbs at the start of each file with an
`# SPDX-License-Identifier: Apache-2.0` string. It also fixes existing
uses to be consistent in capitalization, and to be placed above any
copyright notices.
This removes nearly 3000 lines of boilerplate from the project (only
python files), which no developer cares to look at.
SPDX is in common use, particularly in the Linux kernel, and is the
recommended format for Meson's own `project(license: )` field
Certain envs may not support invoking itstool by itself directly as a script
as shebang lines are not supported, such as under cmd.exe shells on Windows,
that are normally used for Visual Studio (and the like, such as clang-cl)
builds.
This will call the corresponding interpreter to invoke itstool when needed, so
that itstool can be properly run, even if shebang lines are not supported by
the env.
This will fix building appstream on Windows using clang-cl, for instance.
Don't assume itstool, msgfmt et al. are just magically on the path.
Normally for commands being processed in build.ninja we'd look up the
program in order to run it. Offer the same guarantee for programs being
passed through an awkward script wrapper.