codegen: Don't pass CCodeFunctionCall to NULL-aware free macro
codegen: Don't pass CCodeFunctionCall to NULL-aware free macro

This resulted in invalid C code:
    error: lvalue required as left operand of assignment

GNOME/vala,frida/vala,frida/vala,GNOME/vala,frida/vala,GNOME/vala,frida/vala,frida/vala,GNOME/vala