The GLSL SPIR-V compiler is part of the Vulkan SDK and may be used
by projects for compiling shaders as part of the build process.
This is not strictly required to build a Vulkan application, which
is why the variable is not part of the REQUIRED_VARs for the module.
Before Vulkan 1.0.42, the SDK would add the Bin directory to `PATH`,
which was confusing the 32-bit search on Windows. Avoid such confusion
by ignoring the `PATH` when looking for the 32-bit version.
Vulkan 1.0.42 fixed the whole problem by moving the libraries into Lib,
Lib32, so this is strictly a compatibility fix for old SDKs.
Per-source copyright/license notice headers that spell out copyright holder
names and years are hard to maintain and often out-of-date or plain wrong.
Precise contributor information is already maintained automatically by the
version control tool. Ultimately it is the receiver of a file who is
responsible for determining its licensing status, and per-source notices are
merely a convenience. Therefore it is simpler and more accurate for
each source to have a generic notice of the license name and references to
more detailed information on copyright holders and full license terms.
Our `Copyright.txt` file now contains a list of Contributors whose names
appeared source-level copyright notices. It also references version control
history for more precise information. Therefore we no longer need to spell
out the list of Contributors in each source file notice.
Replace CMake per-source copyright/license notice headers with a short
description of the license and links to `Copyright.txt` and online information
available from "https://cmake.org/licensing". The online URL also handles
cases of modules being copied out of our source into other projects, so we
can drop our notices about replacing links with full license text.
Run the `Utilities/Scripts/filter-notices.bash` script to perform the majority
of the replacements mechanically. Manually fix up shebang lines and trailing
newlines in a few files. Manually update the notices in a few files that the
script does not handle.
