Support for shader mutation

Bug: 36025103

Test: cts-tradefed run singleCommand cts-dev --module CtsGraphicsTestCases
Test: cts-tradefed run singleCommand cts-dev --module CtsUiRenderingTestCases
Test: manually inspected for leaks via SK_TRACK_SHADER_LIFETIME and forcing a GC after ComposeShaderTest

Change-Id: Ib5d33a80d2f9f468705806b05832e753508143cc
10 files changed