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
The script will manually delete all custom_target outputs that are
directories instead of files. This is needed because on platforms other
than Windows, Ninja only deletes directories while cleaning if they are
empty.
Closes#1220
Dylan Baker