[K/N][build] Don't use srcRoot in compdb tasks

The CompileToBitcode task has two options to specify sources:
srcDirs and srcRoot. Thus there may be a situation when sources
are specified using srcDirs only and srcRoot doesn't exists (e.g.
compilation of googletest and googlemock, see RuntimeTestingPlugin.kt).

In this case a generated compilation database will contain
a path to a directory which doesn't exist causing error messages
during CLion import. This patch fixes this by getting rid of using
srcRoot in combdb tasks.

kotlin-native/build-tools/src/main/kotlin/org/jetbrains/kotlin/CompilationDatabase.kt

@@ -54,7 +54,6 @@ internal data class Entry(
 }
 
 open class GenerateCompilationDatabase @Inject constructor(@Input val target: String,
-                                                           @Internal val srcRoot: File,
                                                            @Internal val files: Iterable<File>,
                                                            @Input val executable: String,
                                                            @Input val compilerFlags: List<String>,
@@ -68,10 +67,6 @@ open class GenerateCompilationDatabase @Inject constructor(@Input val target: St
     val outputDirPath: String
         get() = outputDir.absolutePath
 
-    @get:Input
-    val srcRootPath: String
-        get() = srcRoot.absolutePath
-
     @get:Input
     val pathsToFiles: Iterable<String>
         get() = files.map { it.absolutePath }
@@ -81,7 +76,7 @@ open class GenerateCompilationDatabase @Inject constructor(@Input val target: St
         val plugin = project.extensions.getByType<ExecClang>()
         val executable = plugin.resolveExecutable(executable)
         val args = listOf(executable) + compilerFlags + plugin.clangArgsForCppRuntime(target)
-        val entries: List<Entry> = files.map { Entry.create(srcRoot, it, args, outputDir) }
+        val entries: List<Entry> = files.map { Entry.create(it.parentFile, it, args, outputDir) }
         Entry.writeListTo(outputFile, entries)
     }
 }
@@ -128,7 +123,6 @@ fun createCompilationDatabasesFromCompileToBitcodeTasks(project: Project, name:
         project.tasks.create("${task.name}_CompilationDatabase",
                 GenerateCompilationDatabase::class.java,
                 task.target,
-                task.srcRoot,
                 task.inputFiles,
                 task.executable,
                 task.compilerFlags,

kotlin-native/build-tools/src/main/kotlin/org/jetbrains/kotlin/bitcode/CompileToBitcode.kt

@@ -62,6 +62,7 @@ abstract class CompileToBitcodeJob : WorkAction<CompileToBitcodeParameters> {
     }
 }
 
+// TODO: Get rid of storing srcRoot in the task.
 abstract class CompileToBitcode @Inject constructor(
         @Internal val srcRoot: File,
         @Input val folderName: String,

kotlin-native/build-tools/src/main/kotlin/org/jetbrains/kotlin/bitcode/CompileToBitcodePlugin.kt

@@ -43,7 +43,7 @@ open class CompileToBitcodeExtension @Inject constructor(val project: Project) {
 
     fun create(
             name: String,
-            srcDir: File = project.file("src/$name"),
+            srcRoot: File = project.file("src/$name"),
             outputGroup: String = "main",
             configurationBlock: CompileToBitcode.() -> Unit = {}
     ) {
@@ -55,7 +55,7 @@ open class CompileToBitcodeExtension @Inject constructor(val project: Project) {
                 project.tasks.register(
                         "${targetName}${name.snakeCaseToCamelCase().capitalize()}${suffixForSanitizer(sanitizer)}",
                         CompileToBitcode::class.java,
-                        srcDir, name, targetName, outputGroup
+                        srcRoot, name, targetName, outputGroup
                 ).configure {
                     this.sanitizer = sanitizer
                     group = BasePlugin.BUILD_GROUP