Fixes crash when using rr::Array with ENABLE_RR_DEBUG_INFO. This is
because when the LValue ctor calls materialize, this would end up
calling the virtual allocate() function, which would not call the
overridden version in rr::Array as it was not fully constructed yet.
Instead, we go back to having the size stored in Value, and passing it up the
constructor chain.

Note that this effectively reverts "Eliminate the array size from rr::Variable"
(5e16bc45) with some modifications.

Bug: b/174160049
Change-Id: I83cec95a74f32ef7276ed60f979a4c32f571eb8a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/50809
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>