samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/cudaconst2.t

@@ -0,0 +1,14 @@
+if not terralib.cudacompile then
+	print("CUDA not enabled, not performing test...")
+	return
+end
+
+local const = cudalib.constantmemory(float, 1)
+
+local terra kernel(data: &float)
+end
+
+local M = terralib.cudacompile({
+    kernel = kernel,
+    const = const
+})