Convert ES3 uniform block precision mismatch test to positive test.

- Rename dEQP-GLES3.functional.shaders.linkage.uniform.block.precision_mismatch
  to ..differing_precision and change expectation to expect no compile failure.
  New behavior matches resolution of Khronos bug 10287.

Bug: 21326228
Change-Id: Ibe6d8899c3dee061f5661b7e63e2d7e653232a8b
3 files changed