Mark variadic argument tests as requiring x86_64

Author: misonijnik

test/Feature/VarArgByValOld.c

@@ -1,3 +1,6 @@
+// Variadic functions are only supported on x86_64
+// REQUIRES: x86_64
+
 // REQUIRES: lt-llvm-15.0
 /* This test checks that KLEE correctly handles variadic arguments with the
    byval attribute */
@@ -128,4 +131,4 @@ int main() {
   struct foo f2 = {10, 20, 30, 40, 50, 60, 70};
   struct bar b2 = {1, 3, 5, 7, 9};
   test2(i, l, i, f, l, b, f2, b2);
-}
+}