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
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.
Dylan Baker