SkJumper: everyone gets a start_pipeline().

Windows needs this as a shim to switch to the System V ABI and back.

Other platforms need it too, if only to make UBSAN happy about calling
functions through the correct function pointers.

One day maybe we can move the looping logic inside start_pipeline?

Change-Id: I47d9ef48752becc6c43fc052b12a540c157bcaaa
Reviewed-on: https://skia-review.googlesource.com/8542
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
3 files changed