3.5.15 Omitting promotion on arguments of vararg function (mcs51, ds390, mos6502, mos65c02, pic14 and pic16 only)

Arguments to vararg functions are not promoted when explicitly cast. This feature is only enabled when the compiler is invoked using --std-sdccxx. This breaks compability with the C standards, so linking code compiled with --std-sdccxx with code compiled using --std-cxx can result in failing programs when arguments to vararg functions are explicitly cast. Note: xx is a placeholder for the desired version of the C standard.