Support hint sizes of arrays

[zaikunzhang]

Dear Clang.jl maintainers,

First of all, thank you very much for this wonderful package!

This issue is motivated by the following discussion:

#443

It might be desirable to support double A[m*n], which is already supported by Clang, and is informative and user-friendly.

In PRIMA, such expressions are used in the public header prima.h. We will remove them for the moment in order to user Clang.jl. However, we do hope to restore them in the future when Clang.jl supports. See libprima/prima#76.

Thanks.

Zaikun

[Gnimuc]

I just added a quick fix in #445. General rules for variable arrays are added, so variable arrays in the function prototype should work now. However, it's not trivial to map a C struct with variable arrays to a Julia type, which means #445 may introduce other bugs...

[Gnimuc]

In fact, variable array structs are rarely used in a public C header, so I guess maybe it's OK to merge that PR.

[zaikunzhang]

Thank you @Gnimuc very much for your swift response. No hurry. We can just remove the sizes for the moment while waiting for a solid implementation.