This patch fixes parts of the PR 49324: There was a deep copy missing 
for assigning an array constructor of a DT with allocatable components.

Whether a deep copy is done, depends on a flag. I think the flag has 
been added to avoid a deep copy and multiple evaluation for functions, 
which return DT w/ allocatable components, and for user-defined operators.

Remains to do be done:
- RESHAPE is mishandled (design error): No deep copy.
- Reallocate on assignment fails (missing NULL initialization of the 
malloced memory).

Build and regtested on x86-64-linux. OK?

Tobias