This patch improves handling of struct/union flags:
1. You can now specify a typedef with "*". Previously it failed like
this:
crash> *acct_t ffff8800982ad520
*: invalid argument
2. Report an error if a non-structured type is used, instead of
giving no output, e.g.:
crash> *pid_t
*: invalid argument
3. Produce an error message if the type does not match the command:
crash> union page
union: data type mismatch: page is not a union
crash> struct thread_union
struct: data type mismatch: thread_union is not a struct
Additionaly, these checks are now performed early, that is before
entering the main printing loop.
Signed-off-by: Petr Tesarik <ptesarik(a)suse.cz>