Update GenCSuite, partially revert "Fix verification sub-suite for GenC"

src/test/scala/leon/genc/GenCSuite.scala

@@ -189,8 +189,7 @@ class GenCSuite extends LeonRegressionSuite {
     override def suiteName = "Verification Suite For GenC"
 
     // Add a timeout for the verification
-    override def optionVariants =
-      super.optionVariants map { opts => "--timeout=5" :: opts }
+    override val optionVariants = List(List("--solvers=smt-z3,ground"))
   }
 
   // Run verification suite as a nested suite

src/test/scala/leon/regression/verification/VerificationSuite.scala

@@ -19,7 +19,7 @@ import org.scalatest.{Reporter => _, _}
 // This is because we compile all tests from each folder together.
 trait VerificationSuite extends LeonRegressionSuite {
 
-  def optionVariants: List[List[String]]
+  val optionVariants: List[List[String]]
   val testDir: String
 
   val ignored: Seq[String] = Seq()

src/test/scala/leon/regression/verification/XLangVerificationSuite.scala

@@ -9,7 +9,7 @@ import leon.solvers.SolverFactory
 // This is because we compile all tests from each folder together.
 class XLangVerificationSuite extends VerificationSuite {
 
-  def optionVariants: List[List[String]] = {
+  val optionVariants: List[List[String]] = {
     val isZ3Available = SolverFactory.hasZ3
 
     List(
@@ -25,3 +25,4 @@ class XLangVerificationSuite extends VerificationSuite {
   val testDir: String = "regression/verification/xlang/"
   override val desugarXLang = true
 }
+