Adding companion main class to generate GCD.v verilog source (#126)

src/main/scala/gcd/GCD.scala

@@ -3,6 +3,8 @@
 package gcd
 
 import chisel3._
+// _root_ disambiguates from package chisel3.util.circt if user imports chisel3.util._
+import _root_.circt.stage.ChiselStage
 
 /**
  * Compute GCD using subtraction method.
@@ -32,3 +34,13 @@ class GCD extends Module {
  io.outputGCD := x
  io.outputValid := y === 0.U
 }
+
+/**
+ * Generate Verilog sources and save it in file GCD.v
+ */
+object GCD extends App {
+ ChiselStage.emitSystemVerilogFile(
+ new GCD,
+ firtoolOpts = Array("-disable-all-randomization", "-strip-debug-info")
+ )
+}