python-selinux: fix cross-compilation, add test.sh

Add --no-build-isolation to PYTHON_SETUP_ARGS. Without it, pip creates
an isolated build environment which fails during cross-compilation
because _sysconfigdata is missing for the target arch.

Add test.sh with basic import and API sanity checks.

Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>

lang/python/python-selinux/test.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+[ "$1" = python3-selinux ] || exit 0
+
+python3 - <<'EOF'
+import selinux
+
+# Verify key functions are available from the C extension
+assert hasattr(selinux, 'is_selinux_enabled'), "is_selinux_enabled missing"
+assert hasattr(selinux, 'getfilecon'), "getfilecon missing"
+assert hasattr(selinux, 'matchpathcon'), "matchpathcon missing"
+assert hasattr(selinux, 'selinux_getenforcemode'), "selinux_getenforcemode missing"
+assert hasattr(selinux, 'security_check_context'), "security_check_context missing"
+assert hasattr(selinux, 'context_new'), "context_new missing"
+
+# Validate context parsing (works without a running SELinux system)
+ctx = selinux.context_new("system_u:object_r:bin_t:s0")
+assert ctx is not None, "context_new returned None"
+assert selinux.context_type_get(ctx) == "bin_t"
+assert selinux.context_role_get(ctx) == "object_r"
+assert selinux.context_user_get(ctx) == "system_u"
+assert selinux.context_range_get(ctx) == "s0"
+
+print("python3-selinux OK")
+EOF