ci: require external posix tools only when setup installed them

setup-external-tools always exits 0 because each sub-target tolerates
failure, so POSIX_REQUIRE_EXTERNAL_TOOLS was set even with no tools
installed and the suite then hard-failed on the missing suites.

.github/workflows/posix-compliance.yml

@@ -249,13 +249,15 @@ jobs:
         # Note: External tools setup is now optional and won't fail the build
         if [ "${{ github.event.inputs.enable_external_tests }}" = "true" ]; then
           echo "Setting up external POSIX testing tools..."
-          if make -f posix_Makefile setup-external-tools; then
-            # Make external tools mandatory when explicitly requested and successfully set up
+          make -f posix_Makefile setup-external-tools || true
+          # setup-external-tools exits 0 even when a sub-target failed, so
+          # require the tools only when they are actually installed
+          if [ -d external_tools/pjdfstest ] && command -v nfstest_posix >/dev/null 2>&1; then
             export POSIX_REQUIRE_EXTERNAL_TOOLS="true"
             echo "POSIX_REQUIRE_EXTERNAL_TOOLS=true" >> $GITHUB_ENV
             echo "✅ External tools setup completed successfully"
           else
-            echo "⚠️  External tools setup failed - continuing with basic tests only"
+            echo "⚠️  External tools setup incomplete - continuing with basic tests only"
             echo "External tools will be skipped but tests will continue"
             echo "This is expected behavior when build tools are not available"
           fi