Hi,

This patch tries to improve diagnostic for wrong type name in function 
declaration. It also changes the algorithm of function 
c_parser_parms_list_declarator. If one of parameter declaration is wrong, 
c_parser_parms_list_declarator would return NULL, not an empty parameter 
information struct. A test case is added to test this change.

Bootstrapped and tested on i686-pc-linux-gnu with enabled c, objc and c++.
Is it ok?

Thanks
Pearly