While adding some new type modifiers I did find a typo in my original
patch, so I decided to add some testcases to make sure no regressions
were introduced. This is the same patch as the original, but with the
typo in modified_type_die fixed that could accidentally add an extra
layer of type modifi
modified_type_die and add_type_attribute take two separate arguments
for whether the type should be const and/or volatile. To help add
more type modifiers pass the requested modifiers as one flag value
to these functions. And introduce helper functions dw_mod_type_flags
and dw_mod_decl_flags to eas
