gitlab: Enable CI for wasm build

Add GitLab CI job that builds QEMU using emscripten. The build runs in the
container defined in tests/docker/dockerfiles/emsdk-wasm32-cross.docker.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
Link: https://lore.kernel.org/r/ade0deb2dc65618a91755590f6729485b4001b94.1745820062.git.ktokunaga.mail@gmail.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
3 files changed