glInstanceID implementation

Implementation attempt for glInstanceID.
Related dEQP tests pass.

Change-Id: I6391699a127cc7c159a2a64e3ffeaa528b611f97
Reviewed-on: https://swiftshader-review.googlesource.com/3412
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/Shader/VertexProgram.cpp b/src/Shader/VertexProgram.cpp
index 14bd5f6..5a516c4 100644
--- a/src/Shader/VertexProgram.cpp
+++ b/src/Shader/VertexProgram.cpp
@@ -665,6 +665,9 @@
 				reg = r.o[i + relativeAddress(r, src)];
 			}
 			break;
+		case Shader::PARAMETER_MISCTYPE:
+			reg.x = Float(r.instanceID);
+			return reg;
 		default:
 			ASSERT(false);
 		}