Declare all inlined variables at the topmost scope possible.

By itself, this is uninteresting and even perhaps slightly
counterproductive (as it separates vardecl from its initializer,
increasing LOC). However, this enables a followup CL
(http://review.skia.org/344665) which allows single-return functions to
be inlined without the creation of a temporary variable at all. This
applies to the majority of fragment processors in a typical Ganesh
hierarchy. This change will greatly reduce the number of inliner-created
temporary copies when compiling a typical tree of FPs.

Change-Id: I03423a13cf35050637dabace4a32973a08a4ed0a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/344764
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
48 files changed