Fix uint precision issue in pipeline barrier tests

Fix uint precision issue in pipeline barrier tests

Add missing highp qualifier for int types in fragment shaders.

Affected tests
dEQP-VK.memory.pipeline_barrier.host_write_uniform_buffer.*
dEQP-VK.memory.pipeline_barrier.host_write_uniform_texel_buffer.*
dEQP-VK.memory.pipeline_barrier.host_write_storage_buffer.*
dEQP-VK.memory.pipeline_barrier.host_write_storage_texel_buffer.*
dEQP-VK.memory.pipeline_barrier.transfer_dst_uniform_buffer.*
dEQP-VK.memory.pipeline_barrier.transfer_dst_uniform_texel_buffer.*
dEQP-VK.memory.pipeline_barrier.transfer_dst_storage_buffer.*
dEQP-VK.memory.pipeline_barrier.transfer_dst_storage_texel_buffer.*
dEQP-VK.memory.pipeline_barrier.all.*
dEQP-VK.memory.pipeline_barrier.all_device.*

VK-GL-CTS issue: 67

Change-Id: I9c78a1c19a06554dd86bf7dbb3c7bc3a96cb72dc