The `.editorconfig` file in this repo is configured to trim all trailing
whitespace regardless of whether the line is modified.
Trims all trailing whitespace in the repository to make the codebase easier
to work with in editors that respect `.editorconfig`.
`git blame` becomes less useful on these lines but it already isn't very useful.
Commands:
```
find . -type f -name '*.h' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
find . -type f -name '*.c' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
```
- Used APIENTRY_LINKAGE in ref_gl to remove duplicate definitions of GL
functions among translation units
- Fixes building ref_gl with -fno-common (GCC 10)
