Use SRCDIR as a working directory

The existing behavior of using the build directory as the working
directory is useful if you want to move/copy the output directory around
and SRCDIR still refers the the source. But, it's more useful to have
the source directory be the working directory. Tools like cpp(__FILE__)
and other debug prints embed relative paths from the working directory.
We also have tools that expect the working directory to be $TOP.

Change-Id: Ia0f1d3c6b7df72d61cf5628efa2baa98bd19775b

cmd/soong_build/main.go

@@ -35,7 +35,7 @@ func main() {
 
 	ctx := soong.NewContext()
 
-	configuration, err := common.NewConfig(srcDir)
+	configuration, err := common.NewConfig(srcDir, bootstrap.BuildDir)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "%s", err)
 		os.Exit(1)
@@ -44,5 +44,5 @@ func main() {
 	// Temporary hack
 	//ctx.SetIgnoreUnknownModuleTypes(true)
 
-	bootstrap.Main(ctx, configuration, common.ConfigFileName, common.ProductVariablesFileName)
+	bootstrap.Main(ctx, configuration, configuration.ConfigFileName, configuration.ProductVariablesFileName)
 }