HashCombine will be used in more than just BindGroupLayout caching so we
extract it to a separate header. Add a better mixing constant for 64bit
systems.
When a BGL was first created in the cache, it started with an external
refcount of 1 and we then referenced again in
BindGroupLayoutBuilder::GetResultImpl, causing a leak.
Fix this by referencing in the cache lookup only if the BGL already
exists.
This directory used to contain both the state tracking code for the
backends, and the common utilities that could be used both by the
backends and the rest of the code. Things are now:
- src/common is utility code for the whole repo
- src/backend contains libNXT's code
- src/utils is utility code that we don't want in libNXT
This commit also changes all includes to use global paths from src/
bacause it had to touch a bunch of #include statements anyway.
Corentin Wallez