Avoid CCE when scalac internally uses compileLate. Fixes #2452

For example, when the `--sourcepath` option is provided
and the refchecks phase compiles an annotation found
on a referenced symbol from the sourcepath.

`compileLate` assumes that all non-sentinel compiler
phases can be down cast to `GlobalPhase`.

This commit changes the two phases in SBT to extend
this instead of `Phase`. This has the knock on benefit
of simplifying the phases by letting the `GlobalPhase.run`
iterator over the list of compilation units and feed them
to us one by one.

I checked that the test case failed before making each
change.

compile/interface/src/main/scala/xsbt/API.scala

@@ -22,16 +22,19 @@ final class API(val global: CallbackGlobal) extends Compat {
   @inline def debug(msg: => String) = if (settings.verbose.value) inform(msg)
 
   def newPhase(prev: Phase) = new ApiPhase(prev)
-  class ApiPhase(prev: Phase) extends Phase(prev) {
+  class ApiPhase(prev: Phase) extends GlobalPhase(prev) {
     override def description = "Extracts the public API from source files."
     def name = API.name
-    def run: Unit =
+    override def run(): Unit =
       {
         val start = System.currentTimeMillis
-        currentRun.units.foreach(processUnit)
+        super.run
         val stop = System.currentTimeMillis
         debug("API phase took : " + ((stop - start) / 1000.0) + " s")
       }
+
+    def apply(unit: global.CompilationUnit): Unit = processUnit(unit)
+
     def processUnit(unit: CompilationUnit) = if (!unit.isJava) processScalaUnit(unit)
     def processScalaUnit(unit: CompilationUnit): Unit = {
       val sourceFile = unit.source.file.file

compile/interface/src/main/scala/xsbt/Analyzer.scala

@@ -19,11 +19,11 @@ final class Analyzer(val global: CallbackGlobal) extends LocateClassFile {
   import global._
 
   def newPhase(prev: Phase): Phase = new AnalyzerPhase(prev)
-  private class AnalyzerPhase(prev: Phase) extends Phase(prev) {
+  private class AnalyzerPhase(prev: Phase) extends GlobalPhase(prev) {
     override def description = "Finds concrete instances of provided superclasses, and application entry points."
     def name = Analyzer.name
-    def run {
-      for (unit <- currentRun.units if !unit.isJava) {
+    def apply(unit: CompilationUnit) {
+      if (!unit.isJava) {
         val sourceFile = unit.source.file.file
         // build list of generated classes
         for (iclass <- unit.icode) {

compile/interface/src/main/scala/xsbt/Dependency.scala

@@ -33,11 +33,11 @@ final class Dependency(val global: CallbackGlobal) extends LocateClassFile {
   import global._
 
   def newPhase(prev: Phase): Phase = new DependencyPhase(prev)
-  private class DependencyPhase(prev: Phase) extends Phase(prev) {
+  private class DependencyPhase(prev: Phase) extends GlobalPhase(prev) {
     override def description = "Extracts dependency information"
     def name = Dependency.name
-    def run: Unit = {
-      for (unit <- currentRun.units if !unit.isJava) {
+    def apply(unit: CompilationUnit): Unit = {
+      if (!unit.isJava) {
         // build dependencies structure
         val sourceFile = unit.source.file.file
         if (global.callback.nameHashing) {