Avoid triggering a rebuild on meson install (#317)

The package was just built, so there's no need to rebuild it right away.
This change makes the `build` command slightly faster, and it avoids
overwriting the generated `.ninja_log` file immediately after it's
been generated during the build.

Author: rgommers

spin/cmds/meson.py

@@ -417,6 +417,7 @@ def build(
         _meson_cli()
         + [
             "install",
+            "--no-rebuild",
             "--only-changed",
             "-C",
             build_dir,