Calculate size of array of stubbed type

Calculate size of array of stubbed type

Sizes of stubbed types are calculated on demand in check_typedef, so the
same must also be done for arrays of stubbed types.

A stubbed type is usually a structure that has only been forward declared,
but can also happen if the structure has a virtual function that's not
inline in the class definition.

For these stubbed types, the size must be recalculated once the full
definition is available.

gdb/ChangeLog:

2020-04-30  Hannes Domani  <ssbssa@yahoo.de>

	PR gdb/18706
	* gdbtypes.c (check_typedef): Calculate size of array of
	stubbed type.

gdb/testsuite/ChangeLog:

2020-04-30  Hannes Domani  <ssbssa@yahoo.de>

	PR gdb/18706
	* gdb.cp/stub-array-size.cc: New test.
	* gdb.cp/stub-array-size.exp: New file.
	* gdb.cp/stub-array-size.h: New test.
	* gdb.cp/stub-array-size2.cc: New test.