resolve_indirect() does not resolve indirect encodings #61

In function value::resolve_indirect(DW_AT name) a local variable DW_FORM form is defined, so the resolve is performed on this local variable. The attribute DW_FORM form in class Value is not changed at all.

Due to this, I see an issue that when the form is indirect, it throws exception in function value::as_reference():
throw value_type_mismatch("cannot read " + to_string(typ) + " as reference");