[REG2.064a] fix Issue 10736 - Regression (2.064 git-head): Instantiation failure triggered by module import and module order

http://d.puremagic.com/issues/show_bug.cgi?id=10736

The regression is introduced by recent [Phobos change](https://github.com/D-Programming-Language/phobos/pull/992), but the root cause is premature semantic3 invocation for template instances.

In the reduced test case, `test10736b` instantiates `chunks` template function, then it instantiates `Chunks!(int[])`. The instance object will be inserted to `test10736a` member because it is the first module that importing `test10736c`. But in this time, `test10736a` module's semantic3 is already done, then `Chunks!(int[])` would immediately invoke its semantic3, then `Chunks!(int[]).opSlice` refers *not yet instantiation finished* `chunks` template.

To avoid the forward reference problem, we should defer semantic3 of template instances which inserted to module scope.