Improvements to uniform handling in runtime SkSL

- Support array uniforms
- Fix cases where the read head wasn't aligned in onSetData
- Default to float as the CType for half. (half4 was using
  PMColor, and other half types required a layout(ctype...)

Change-Id: I63cb1706071668de0ab80f3d812cd9ad29ff9651
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/258808
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed