Fix bogus zero-length array test.

Issue 7175 was about .ptr always giving null for a zero-length
static array in a struct, despite the fact that the struct has
size 1 and thus certainly a non-null address.

The test case as modified by 36c9b64, however, checks that a
free-standing zero-length static array on the stack has an
address, which is quite a different scenario. From the spec,
I don't see a reason why zero-sized objects should need any
memory associated with them, so I am reluctant to pessimize
LDC's codegen over this.
[Refactoring] Add helper function for array-op classification
fix Issue 13382 - [e2ir] compare string to int - leads to ICE in e2ir.c 1902
Merge pull request #3729 from klickverbot/fix-7175-test

Fix bogus zero-length array test.
fix Issue 13476 - Writing stubs for dynamically loaded functions no longer works. (circular reference)
need explicit function call for c_long_double
Merge pull request #3982 from 9rnsr/fix13382

Issue 13382 - [e2ir] compare string to int - leads to ICE in e2ir.c 1902
fix Issue 13479 - Templates not emitted when instantiated in mixins mixed in functions

In the PR #3948, I changed the position where `TemplateInstance`s are inserted.

https://github.com/D-Programming-Language/dmd/pull/3948/files#diff-0477a1d81a6a920c99362954179c59c8R5937

But, I didn't notice that glue-layer does not handle `TemplateInstance`s in local members.
Add test case for issue 13478.

The issue was a 2.066 regression that has been fixed differently
on master in the meantime. This adds the test case from the
2.066 branch commit 972c90f.
Merge pull request #3991 from 9rnsr/fix13479

[REG2.067a] Issue 13479 - Templates not emitted when instantiated in mixins mixed in functions
Merge pull request #3996 from klickverbot/issue-13478-tests

Add test case for issue 13478.
Merge pull request #3990 from WalterBright/fix-long-double

need explicit function call for c_long_double
Merge pull request #3989 from 9rnsr/fix13476

[REG2.065] Issue 13476 - Writing stubs for dynamically loaded functions no longer works. (circular reference)
add C++ mangling c_long and c_ulong
resolve warning in typinf.c
Merge pull request #3999 from WalterBright/typinf-warning

resolve warning in typinf.c
fix Issue 13481 - bug with inferring attributes from built-in properties
fix Issue 13472 - trying to insert a null into an array of object segfaults the compiler
Merge pull request #3994 from 9rnsr/fix13472

[REG2.066] Issue 13472 - trying to insert a null into an array of object segfaults the compiler
Merge pull request #4001 from 9rnsr/fix13481

Issue 13481 - bug with inferring attributes from built-in properties