Support passing lint baseline to doclava

There are many issues in the docs, so allow specifying a baseline
file that allows existing lint errors in doclava.

Bug: 217734059
Test: m docs
Change-Id: I8997e47a497e1366247e8354be492805f300a16e

java/droiddoc.go

@@ -136,6 +136,9 @@ type DroiddocProperties struct {
 	// At some point, this might be improved to show more warnings.
 	Todo_file *string `android:"path"`
 
+	// A file containing a baseline for allowed lint errors.
+	Lint_baseline *string `android:"path"`
+
 	// directory under current module source that provide additional resources (images).
 	Resourcesdir *string
 
@@ -665,6 +668,10 @@ func (d *Droiddoc) doclavaDocsFlags(ctx android.ModuleContext, cmd *android.Rule
 			ImplicitOutput(android.PathForModuleOut(ctx, String(d.properties.Todo_file)))
 	}
 
+	if String(d.properties.Lint_baseline) != "" {
+		cmd.FlagWithInput("-lintbaseline ", android.PathForModuleSrc(ctx, String(d.properties.Lint_baseline)))
+	}
+
 	if String(d.properties.Resourcesdir) != "" {
 		// TODO: should we add files under resourcesDir to the implicits? It seems that
 		// resourcesDir is one sub dir of htmlDir