always run xlang

src/main/scala/leon/GlobalOptions.scala

src/main/scala/leon/Main.scala

src/main/scala/leon/utils/PreprocessingPhase.scala

...resources/regression/frontends/error/simple/Asserts.scala

...rces/regression/verification/xlang/invalid/Asserts2.scala

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

...test/scala/leon/regression/frontends/FrontEndsSuite.scala

...st/scala/leon/regression/testcases/TestCasesCompile.scala

...cala/leon/regression/verification/VerificationSuite.scala

...st/scala/leon/regression/xlang/XLangDesugaringSuite.scala