vulpix: pass -classpath to javac too

Otherwise the tastyBootstrap test failed when compiling the .java files
added in the previous commit that depend on scala-asm.

Author: smarter

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -336,9 +336,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
         val fullArgs = Array(
           "javac",
           "-encoding", "UTF-8",
-          "-classpath",
-          s"${Properties.scalaLibrary}${JFile.pathSeparator}${targetDir.getAbsolutePath}"
-        ) ++ flags.all.takeRight(2) ++ fs
+        ) ++ flags.javacFlags ++ fs
 
         val process = Runtime.getRuntime.exec(fullArgs)
         val output = Source.fromInputStream(process.getErrorStream).mkString

compiler/test/dotty/tools/vulpix/TestFlags.scala

@@ -20,6 +20,14 @@ final case class TestFlags(
     TestFlags(defaultClassPath, s"$runClassPath${JFile.pathSeparator}$classPath", options)
 
   def all: Array[String] = Array("-classpath", defaultClassPath) ++ options
+
+  /** Subset of the flags that should be passed to javac. */
+  def javacFlags: Array[String] = {
+    val flags = all
+    val cp = flags.dropWhile(_ != "-classpath").take(2)
+    val output = flags.dropWhile(_ != "-d").take(2)
+    cp ++ output
+  }
 }
 
 object TestFlags {