Add missing soong_docs inputs

Specifically, make Android.bp.list and soong.variables explicit inputs

While this is not a comprehensive list of all inputs
of this action (as the action depends on all blueprint
files in the source tree), this is closer to the truth.

This is a rollforward CL, which was originally rolled
back, as path validation failed for when OUT_DIR was
an absolute path. Validation has now been relaxed.

Test: Manually verified ninja output, checkbuild approved validation
  for aosp-crosshatch, and manually ran frameworks/rs/build_rs.py with
  patch fix
Change-Id: I4eb0d517f57336dd54eaa4bd31f46df9e93e6da2
diff --git a/android/config.go b/android/config.go
index 16f3d73..c25900b 100644
--- a/android/config.go
+++ b/android/config.go
@@ -93,8 +93,9 @@
 
 	deviceConfig *deviceConfig
 
-	srcDir   string // the path of the root source directory
-	buildDir string // the path of the build output directory
+	srcDir         string // the path of the root source directory
+	buildDir       string // the path of the build output directory
+	moduleListFile string // the path to the file which lists blueprint files to parse.
 
 	env       map[string]string
 	envLock   sync.Mutex
@@ -316,7 +317,7 @@
 
 // New creates a new Config object.  The srcDir argument specifies the path to
 // the root source directory. It also loads the config file, if found.
-func NewConfig(srcDir, buildDir string) (Config, error) {
+func NewConfig(srcDir, buildDir string, moduleListFile string) (Config, error) {
 	// Make a config with default options
 	config := &config{
 		ConfigFileName:           filepath.Join(buildDir, configFileName),
@@ -328,7 +329,8 @@
 		buildDir:          buildDir,
 		multilibConflicts: make(map[ArchType]bool),
 
-		fs: pathtools.NewOsFs(absSrcDir),
+		moduleListFile: moduleListFile,
+		fs:             pathtools.NewOsFs(absSrcDir),
 	}
 
 	config.deviceConfig = &deviceConfig{