drop -scansource setting

Author: bishabosha

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -17,7 +17,6 @@ class ScalaSettings extends Settings.SettingGroup {
   val javabootclasspath: Setting[String] = PathSetting("-javabootclasspath", "Override java boot classpath.", Defaults.javaBootClassPath) withAbbreviation "--java-boot-class-path"
   val javaextdirs: Setting[String] = PathSetting("-javaextdirs", "Override java extdirs classpath.", Defaults.javaExtDirs) withAbbreviation "--java-extension-directories"
   val sourcepath: Setting[String] = PathSetting("-sourcepath", "Specify location(s) of source files.", Defaults.scalaSourcePath) withAbbreviation "--source-path"
-  val scansource: Setting[Boolean] = BooleanSetting("-scansource", "Scan source files to locate classes for which class-name != file-name") withAbbreviation "--scan-source"
   val sourceroot: Setting[String] = PathSetting("-sourceroot", "Specify workspace root directory", ".")
   val targetroot: Setting[String] = PathSetting("-targetroot", "Specify output directory", "")