Roll external/skia fd773fb50..b3d0f7c79 (2 commits)

https://skia.googlesource.com/skia.git/+log/fd773fb50..b3d0f7c79

2017-05-17 ethannicholas@google.com skslc SPIR-V mod support
2017-05-17 recipe-roller@chromium.org Roll recipe dependencies (trivial).

Test: Presubmit checks will test this change.
Change-Id: Ieffe7f0b102fe53f352f9b40067cd25d511fa378