Launch options & multi inputs for single-source RS

Bug: 23535985

Also renamed rsParallelFor to rsForEach.
Added checks for number of allocations to rsForEach matching kernel function
expectation.

Added slang tests.

Removed code from RSContext for remembering the rs_allocation AST subtree.

Change-Id: Ibc22bd5e9585a4471b15920ef60fe1fe2312de49
28 files changed