Fix Issue 9803 & 10636 with minimallyInitializedArray

== 9803 ==
http://d.puremagic.com/issues/show_bug.cgi?id=9803
`arrayAllocImpl` was failing to properly propagate the `minimallyInitialized` information on recursion, which meant 2+D arrays where never initialized

== 10636 ==
http://d.puremagic.com/issues/show_bug.cgi?id=10636
Basically, the intialization scheme triggered postblit and destruction. There is no need for that. Simple memory initialization is better, and faster too (including cases without postblit).

Also, this deactivates initialization with CTFE, since elements are already initialized in CTFE anyways.