Run tests in CI

[kpp]

cargo test gives me warnings:

$ cargo test
warning: output filename collision.
The example target `info_core` in package `ocl-core v0.11.1 (ocl/ocl-core)` has the same output filename as the example target `info_core` in package `ocl v0.19.2 (ocl/ocl)`.
Colliding filename is: ocl/target/debug/examples/info_core
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.
warning: output filename collision.
The example target `trivial` in package `ocl-core v0.11.1 (ocl/ocl-core)` has the same output filename as the example target `trivial` in package `ocl v0.19.2 (ocl/ocl)`.
Colliding filename is: ocl/target/debug/examples/trivial
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.

Also the testsuite requires a lot of packages:

   Compiling glfw-sys v3.3.0
   Compiling wayland-client v0.12.5
   Compiling wayland-protocols v0.12.5
   Compiling tempfile v3.0.8
   Compiling glutin v0.12.2
   Compiling gl v0.9.0
   Compiling sdl2 v0.31.0

And

error: failed to run custom build command for `glfw-sys v3.3.0`
process didn't exit successfully: `ocl/target/debug/build/glfw-sys-7caa1440caf3a20a/build-script-build` (exit code: 101)
--- stdout
running: "cmake" ".cargo/registry/src/github.com-1ecc6299db9ec823/glfw-sys-3.3.0/." "-DGLFW_BUILD_EXAMPLES=OFF" "-DGLFW_BUILD_TESTS=OFF" "-DGLFW_BUILD_DOCS=OFF" "-DCMAKE_INSTALL_LIBDIR=lib" "-DCMAKE_INSTALL_PREFIX=ocl/target/debug/build/glfw-sys-34282c5bfb8321b7/out" "-DCMAKE_C_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_C_COMPILER=/usr/bin/cc" "-DCMAKE_CXX_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_CXX_COMPILER=/usr/bin/c++" "-DCMAKE_BUILD_TYPE=Debug"
-- Using X11 for window creation

Do we really need to install sdl, glfw, wayland to run tests?

[dmarcuse]

I'm assuming they're required to test OpenGL interop to some extent, but I can't say I'm experienced enough to know whether there's a way to run tests without them.

[c0gent]

We really only need to run the tests in the ocl sub-crate.