Dear Fortranners,

some instances of valid constant array constructors did lead to ICEs.
It turned out that on the one hand we need to attempt simplification of
elements of the constructor, especially when we encounter parenthesized
expression.  On the other hand the occurence of type specs and empty
constructors need to be handled more gracefully.

Parts of the PR have been fixed previously, so the remaining part was
rather simple.

The testcase is based on Gerhards latest example attached to the PR.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Given the simplicity of the patch and that it is an ICE on valid code,
would this qualify for later application to 11-branch?

Thanks,
Harald