Added gl_FragDepth

Change-Id: I9e70cd5e230a86ef3e4bed1884ede14a128c2d67
Reviewed-on: https://swiftshader-review.googlesource.com/3992
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
3 files changed