LibC: Do not include suppressed assignments in scanf return value

Author: https://github.com/rouseabout 🔰
Commit: 31079a56d7
Pull-request: https://github.com/SerenityOS/serenity/pull/12570
Reviewed-by: https://github.com/TSultanov

Tests/LibC/TestScanf.cpp

@@ -178,6 +178,7 @@ const TestSuite test_suites[] {
     { "%llu", "9223372036854775810", 1, 1, { unsignedlonglongarg0 }, { to_value_t(9223372036854775810ULL) } },
     { "%n", "", 0, 1, { intarg0 }, { to_value_t(0) } },
     { "%d %n", "1 a", 1, 2, { intarg0, intarg1 }, { to_value_t(1), to_value_t(2) } },
+    { "%*d", "  42", 0, 0, {}, {} },
 };
 
 bool g_any_failed = false;