Do not output return as last statement

[rfalke]

Exe: https://github.com/rfalke/decompiler-subjects/blob/master/from_holdec/dmi/cfg/ia32_elf/subject.exe
Boomerang: boomerang-cli v0.3.99-alpha-1757-gd6a5867

Output (see https://github.com/rfalke/decompiler-subjects/blob/master/from_holdec/dmi/cfg/ia32_elf/by_boomerang-ng.c):

void basic_1_if(__size32 param1)
{
    if (param1 == 42) {
        puts("if block");
    }
    else {
    }
    return;
}

The return without a value as the last statement is just noise and serves no purpose.