Rename millImport variable to metaBuild (#3848)

We have various things to import, but this parameter is for the
enabled-state of the meta-build, so reflect it in the name.

Pull request: #3848

runner/src/mill/runner/FileImportGraph.scala

@@ -13,15 +13,15 @@ import scala.collection.mutable
  * @param ivyDeps
  * @param importGraphEdges
  * @param errors
- * @param millImport If `true`, a meta-build is enabled
+ * @param metaBuild If `true`, a meta-build is enabled
  */
 @internal
 case class FileImportGraph(
     seenScripts: Map[os.Path, String],
     repos: Seq[(String, os.Path)],
     ivyDeps: Set[String],
     errors: Seq[String],
-    millImport: Boolean,
+    metaBuild: Boolean,
     buildFile: String
 )
 

runner/src/mill/runner/MillBuildBootstrap.scala

@@ -107,7 +107,7 @@ class MillBuildBootstrap(
           output
         )
 
-        if (parsedScriptFiles.millImport) evaluateRec(depth + 1)
+        if (parsedScriptFiles.metaBuild) evaluateRec(depth + 1)
         else {
           val bootstrapModule =
             new MillBuildRootModule.BootstrapModule()(

runner/src/mill/runner/MillBuildRootModule.scala

@@ -193,13 +193,13 @@ abstract class MillBuildRootModule()(implicit
 
   override def sources: T[Seq[PathRef]] = Task {
     scriptSources() ++ {
-      if (parseBuildFiles().millImport) super.sources()
+      if (parseBuildFiles().metaBuild) super.sources()
       else Seq.empty[PathRef]
     }
   }
 
   override def resources: T[Seq[PathRef]] = Task {
-    if (parseBuildFiles().millImport) super.resources()
+    if (parseBuildFiles().metaBuild) super.resources()
     else Seq.empty[PathRef]
   }