Add missing is_fuchsia to system_utils selection.
Add missing is_fuchsia to system_utils selection.

This fixes a build break because of 046fa0efc44d3ac5d.
See: https://crrev.com/c/898591

Bug: angleproject:2333
Change-Id: I6a4cb60dd2d2958ea71aaa27f1429233c2787fb4
Reviewed-on: https://chromium-review.googlesource.com/922878
Reviewed-by: Scott Graham <e134406e1863f3b48b0795831afac5c0595efb36@chromium.org>
Commit-Queue: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle